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//////////////////////////////////////////////////////////////////////
// LibFile: arrays.scad
// List and Array manipulation functions.
// Includes:
// include <BOSL2/std.scad>
//////////////////////////////////////////////////////////////////////
// Section: Terminology
// - **List**: An ordered collection of zero or more items. ie: `["a", "b", "c"]`
// - **Vector**: A list of numbers. ie: `[4, 5, 6]`
// - **Array**: A nested list of lists, or list of lists of lists, or deeper. ie: `[[2,3], [4,5], [6,7]]`
// - **Dimension**: The depth of nesting of lists in an array. A List is 1D. A list of lists is 2D. etc.
// - **Set**: A list of unique items.
// Section: List Query Operations
// Function: is_homogeneous()
// Usage:
// is_homogeneous(list,depth)
// Description:
// Returns true when the list have elements of same type up to the depth `depth`.
// Booleans and numbers are not distinguinshed as of distinct types.
// Arguments:
// list = the list to check
// depth = the lowest level the check is done
// Example:
// is_homogeneous( [[1,["a"]], [2,["b"]]] ) // Returns true
// is_homogeneous( [[1,["a"]], [2,[true]]] ) // Returns false
// is_homogeneous( [[1,["a"]], [2,[true]]], 1 ) // Returns true
// is_homogeneous( [[1,["a"]], [2,[true]]], 2 ) // Returns false
// is_homogeneous( [[1,["a"]], [true,["b"]]] ) // Returns true
function is_homogeneous(l, depth=10) =
!is_list(l) || l==[] ? false :
let( l0=l[0] )
[] == [for(i=[1:len(l)-1]) if( ! _same_type(l[i],l0, depth+1) ) 0 ];
function _same_type(a,b, depth) =
(depth==0) ||
(is_undef(a) && is_undef(b)) ||
(is_bool(a) && is_bool(b)) ||
(is_num(a) && is_num(b)) ||
(is_string(a) && is_string(b)) ||
(is_list(a) && is_list(b) && len(a)==len(b)
&& []==[for(i=idx(a)) if( ! _same_type(a[i],b[i],depth-1) ) 0] );
// Function: select()
// Description:
// Returns a portion of a list, wrapping around past the beginning, if end<start.
// The first item is index 0. Negative indexes are counted back from the end.
// The last item is -1. If only the `start` index is given, returns just the value
// at that position.
// Usage:
// select(list,start)
// select(list,start,end)
// Arguments:
// list = The list to get the portion of.
// start = The index of the first item.
// end = The index of the last item.
// Example:
// l = [3,4,5,6,7,8,9];
// select(l, 5, 6); // Returns [8,9]
// select(l, 5, 8); // Returns [8,9,3,4]
// select(l, 5, 2); // Returns [8,9,3,4,5]
// select(l, -3, -1); // Returns [7,8,9]
// select(l, 3, 3); // Returns [6]
// select(l, 4); // Returns 7
// select(l, -2); // Returns 8
// select(l, [1:3]); // Returns [4,5,6]
// select(l, [1,3]); // Returns [4,6]
function select(list, start, end=undef) =
assert( is_list(list) || is_string(list), "Invalid list.")
let(l=len(list))
l==0 ? []
: end==undef?
is_num(start)?
list[ (start%l+l)%l ]
: assert( is_list(start) || is_range(start), "Invalid start parameter")
[for (i=start) list[ (i%l+l)%l ] ]
: assert(is_finite(start), "Invalid start parameter.")
assert(is_finite(end), "Invalid end parameter.")
let( s = (start%l+l)%l, e = (end%l+l)%l )
(s <= e)? [for (i = [s:1:e]) list[i]]
: concat([for (i = [s:1:l-1]) list[i]], [for (i = [0:1:e]) list[i]]) ;
// Function: last()
// Description:
// Returns the last element of a list, or undef if empty.
// Usage:
// last(list)
// Arguments:
// list = The list to get the last element of.
// Example:
// l = [3,4,5,6,7,8,9];
// last(l); // Returns 9.
function last(list) = list[len(list)-1];
// Function: delete_last()
// Description:
// Returns a list of all but the last entry. If input is empty, returns empty list.
// Usage:
// delete_last(list)
function delete_last(list) =
assert(is_list(list))
list==[] ? [] : slice(list,0,-2);
// Function: slice()
// Description:
// Returns a slice of a list. The first item is index 0.
// Negative indexes are counted back from the end. The last item is -1.
// Arguments:
// list = The array/list to get the slice of.
// start = The index of the first item to return.
// end = The index after the last item to return, unless negative, in which case the last item to return.
// Example:
// slice([3,4,5,6,7,8,9], 3, 5); // Returns [6,7]
// slice([3,4,5,6,7,8,9], 2, -1); // Returns [5,6,7,8,9]
// slice([3,4,5,6,7,8,9], 1, 1); // Returns []
// slice([3,4,5,6,7,8,9], 6, -1); // Returns [9]
// slice([3,4,5,6,7,8,9], 2, -2); // Returns [5,6,7,8]
function slice(list,start,end) =
assert( is_list(list), "Invalid list" )
assert( is_finite(start) && is_finite(end), "Invalid number(s)" )
let( l = len(list) )
l==0 ? []
: let(
s = start<0? (l+start): start,
e = end<0? (l+end+1): end
) [for (i=[s:1:e-1]) if (e>s) list[i]];
// Function: in_list()
// Description: Returns true if value `val` is in list `list`. When `val==NAN` the answer will be false for any list.
// Arguments:
// val = The simple value to search for.
// list = The list to search.
// idx = If given, searches the given subindex for matches for `val`.
// Example:
// in_list("bar", ["foo", "bar", "baz"]); // Returns true.
// in_list("bee", ["foo", "bar", "baz"]); // Returns false.
// in_list("bar", [[2,"foo"], [4,"bar"], [3,"baz"]], idx=1); // Returns true.
function in_list(val,list,idx=undef) =
assert( is_list(list) && (is_undef(idx) || is_finite(idx)),
"Invalid input." )
let( s = search([val], list, num_returns_per_match=1, index_col_num=idx)[0] )
s==[] || s==[[]] ? false
: is_undef(idx) ? val==list[s]
: val==list[s][idx];
// Function: min_index()
// Usage:
// min_index(vals,[all]);
// Description:
// Returns the index of the first occurrence of the minimum value in the given list.
// If `all` is true then returns a list of all indices where the minimum value occurs.
// Arguments:
// vals = vector of values
// all = set to true to return indices of all occurences of the minimum. Default: false
// Example:
// min_index([5,3,9,6,2,7,8,2,1]); // Returns: 8
// min_index([5,3,9,6,2,7,8,2,7],all=true); // Returns: [4,7]
function min_index(vals, all=false) =
assert( is_vector(vals) && len(vals)>0 , "Invalid or empty list of numbers.")
all ? search(min(vals),vals,0) : search(min(vals), vals)[0];
// Function: max_index()
// Usage:
// max_index(vals,[all]);
// Description:
// Returns the index of the first occurrence of the maximum value in the given list.
// If `all` is true then returns a list of all indices where the maximum value occurs.
// Arguments:
// vals = vector of values
// all = set to true to return indices of all occurences of the maximum. Default: false
// Example:
// max_index([5,3,9,6,2,7,8,9,1]); // Returns: 2
// max_index([5,3,9,6,2,7,8,9,1],all=true); // Returns: [2,7]
function max_index(vals, all=false) =
assert( is_vector(vals) && len(vals)>0 , "Invalid or empty list of numbers.")
all ? search(max(vals),vals,0) : search(max(vals), vals)[0];
// Function: list_increasing()
// Usage:
// list_increasing(list)
// Description:
// Returns true if the list is (non-strictly) increasing
// Example:
// list_increasing([1,2,3,4]); // Returns: true
// list_increasing([1,3,2,4]); // Returns: false
// list_increasing([4,3,2,1]); // Returns: false
function list_increasing(list) =
assert(is_list(list)||is_string(list))
len([for (p=pair(list)) if(p.x>p.y) true])==0;
// Function: list_decreasing()
// Usage:
// list_decreasing(list)
// Description:
// Returns true if the list is (non-strictly) decreasing
// Example:
// list_decreasing([1,2,3,4]); // Returns: false
// list_decreasing([4,2,3,1]); // Returns: false
// list_decreasing([4,3,2,1]); // Returns: true
function list_decreasing(list) =
assert(is_list(list)||is_string(list))
len([for (p=pair(list)) if(p.x<p.y) true])==0;
// Section: Basic List Generation
// Function: repeat()
// Usage:
// repeat(val, n)
// Description:
// Generates a list or array of `n` copies of the given value `val`.
// If the count `n` is given as a list of counts, then this creates a
// multi-dimensional array, filled with `val`.
// Arguments:
// val = The value to repeat to make the list or array.
// n = The number of copies to make of `val`.
// Example:
// repeat(1, 4); // Returns [1,1,1,1]
// repeat(8, [2,3]); // Returns [[8,8,8], [8,8,8]]
// repeat(0, [2,2,3]); // Returns [[[0,0,0],[0,0,0]], [[0,0,0],[0,0,0]]]
// repeat([1,2,3],3); // Returns [[1,2,3], [1,2,3], [1,2,3]]
function repeat(val, n, i=0) =
is_num(n)? [for(j=[1:1:n]) val] :
assert( is_list(n), "Invalid count number.")
(i>=len(n))? val :
[for (j=[1:1:n[i]]) repeat(val, n, i+1)];
// Function: list_range()
// Usage:
// list_range(n, [s], [e])
// list_range(n, [s], [step])
// list_range(e, [step])
// list_range(s, e, [step])
// Description:
// Returns a list, counting up from starting value `s`, by `step` increments,
// until either `n` values are in the list, or it reaches the end value `e`.
// If both `n` and `e` are given, returns `n` values evenly spread from `s`
// to `e`, and `step` is ignored.
// Arguments:
// n = Desired number of values in returned list, if given.
// s = Starting value. Default: 0
// e = Ending value to stop at, if given.
// step = Amount to increment each value. Default: 1
// Example:
// list_range(4); // Returns [0,1,2,3]
// list_range(n=4, step=2); // Returns [0,2,4,6]
// list_range(n=4, s=3, step=3); // Returns [3,6,9,12]
// list_range(n=5, s=0, e=10); // Returns [0, 2.5, 5, 7.5, 10]
// list_range(e=3); // Returns [0,1,2,3]
// list_range(e=7, step=2); // Returns [0,2,4,6]
// list_range(s=3, e=5); // Returns [3,4,5]
// list_range(s=3, e=8, step=2); // Returns [3,5,7]
// list_range(s=4, e=8.3, step=2); // Returns [4,6,8]
// list_range(n=4, s=[3,4], step=[2,3]); // Returns [[3,4], [5,7], [7,10], [9,13]]
function list_range(n=undef, s=0, e=undef, step=undef) =
assert( is_undef(n) || is_finite(n), "Parameter `n` must be a number.")
assert( is_undef(n) || is_undef(e) || is_undef(step), "At most 2 of n, e, and step can be given.")
let( step = (n!=undef && e!=undef)? (e-s)/(n-1) : default(step,1) )
is_undef(e) ?
assert( is_consistent([s, step]), "Incompatible data.")
[for (i=[0:1:n-1]) s+step*i ]
: assert( is_vector([s,step,e]), "Start `s`, step `step` and end `e` must be numbers.")
[for (v=[s:step:e]) v] ;
// Section: List Manipulation
// Function: reverse()
// Description: Reverses a list/array or string.
// Arguments:
// x = The list or string to reverse.
// Example:
// reverse([3,4,5,6]); // Returns [6,5,4,3]
function reverse(x) =
assert(is_list(x)||is_string(x), str("Input to reverse must be a list or string. Got: ",x))
let (elems = [ for (i = [len(x)-1 : -1 : 0]) x[i] ])
is_string(x)? str_join(elems) : elems;
// Function: list_rotate()
// Usage:
// rlist = list_rotate(list,n);
// Description:
// Rotates the contents of a list by `n` positions left.
// If `n` is negative, then the rotation is `abs(n)` positions to the right.
// If `list` is a string, then a string is returned with the characters rotates within the string.
// Arguments:
// list = The list to rotate.
// n = The number of positions to rotate by. If negative, rotated to the right. Positive rotates to the left. Default: 1
// Example:
// l1 = list_rotate([1,2,3,4,5],-2); // Returns: [4,5,1,2,3]
// l2 = list_rotate([1,2,3,4,5],-1); // Returns: [5,1,2,3,4]
// l3 = list_rotate([1,2,3,4,5],0); // Returns: [1,2,3,4,5]
// l4 = list_rotate([1,2,3,4,5],1); // Returns: [2,3,4,5,1]
// l5 = list_rotate([1,2,3,4,5],2); // Returns: [3,4,5,1,2]
// l6 = list_rotate([1,2,3,4,5],3); // Returns: [4,5,1,2,3]
// l7 = list_rotate([1,2,3,4,5],4); // Returns: [5,1,2,3,4]
// l8 = list_rotate([1,2,3,4,5],5); // Returns: [1,2,3,4,5]
// l9 = list_rotate([1,2,3,4,5],6); // Returns: [2,3,4,5,1]
function list_rotate(list,n=1) =
assert(is_list(list)||is_string(list), "Invalid list or string.")
assert(is_finite(n), "Invalid number")
let (elems = select(list,n,n+len(list)-1))
is_string(list)? str_join(elems) : elems;
// Function: deduplicate()
// Usage:
// deduplicate(list,[close],[eps]);
// Description:
// Removes consecutive duplicate items in a list.
// When `eps` is zero, the comparison between consecutive items is exact.
// Otherwise, when all list items and subitems are numbers, the comparison is within the tolerance `eps`.
// This is different from `unique()` in that the list is *not* sorted.
// Arguments:
// list = The list to deduplicate.
// closed = If true, drops trailing items if they match the first list item.
// eps = The maximum tolerance between items.
// Examples:
// deduplicate([8,3,4,4,4,8,2,3,3,8,8]); // Returns: [8,3,4,8,2,3,8]
// deduplicate(closed=true, [8,3,4,4,4,8,2,3,3,8,8]); // Returns: [8,3,4,8,2,3]
// deduplicate("Hello"); // Returns: "Helo"
// deduplicate([[3,4],[7,2],[7,1.99],[1,4]],eps=0.1); // Returns: [[3,4],[7,2],[1,4]]
// deduplicate([[7,undef],[7,undef],[1,4],[1,4+1e-12]],eps=0); // Returns: [[7,undef],[1,4],[1,4+1e-12]]
function deduplicate(list, closed=false, eps=EPSILON) =
assert(is_list(list)||is_string(list))
let(
l = len(list),
end = l-(closed?0:1)
)
is_string(list) ? str_join([for (i=[0:1:l-1]) if (i==end || list[i] != list[(i+1)%l]) list[i]]) :
eps==0 ? [for (i=[0:1:l-1]) if (i==end || list[i] != list[(i+1)%l]) list[i]] :
[for (i=[0:1:l-1]) if (i==end || !approx(list[i], list[(i+1)%l], eps)) list[i]];
// Function: deduplicate_indexed()
// Usage:
// new_idxs = deduplicate_indexed(list, indices, [closed], [eps]);
// Description:
// Given a list, and indices into it, removes consecutive indices that
// index to the same values in the list.
// Arguments:
// list = The list that the indices index into.
// indices = The list of indices to deduplicate.
// closed = If true, drops trailing indices if what they index matches what the first index indexes.
// eps = The maximum difference to allow between numbers or vectors.
// Examples:
// deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1]); // Returns: [1,4,3,2,0,1]
// deduplicate_indexed([8,6,4,6,3], [1,4,3,1,2,2,0,1], closed=true); // Returns: [1,4,3,2,0]
// deduplicate_indexed([[7,undef],[7,undef],[1,4],[1,4],[1,4+1e-12]],eps=0); // Returns: [0,2,4]
function deduplicate_indexed(list, indices, closed=false, eps=EPSILON) =
assert(is_list(list)||is_string(list), "Improper list or string.")
indices==[]? [] :
assert(is_vector(indices), "Indices must be a list of numbers.")
let( l = len(indices),
end = l-(closed?0:1) )
[ for (i = [0:1:l-1])
let(
a = list[indices[i]],
b = list[indices[(i+1)%l]],
eq = (a == b)? true :
(a*0 != b*0) || (eps==0)? false :
is_num(a) || is_vector(a) ? approx(a, b, eps=eps)
: false
)
if (i==end || !eq) indices[i]
];
// Function: repeat_entries()
// Usage:
// newlist = repeat_entries(list, N)
// Description:
// Takes a list as input and duplicates some of its entries to produce a list
// with length `N`. If the requested `N` is not a multiple of the list length then
// the entries will be duplicated as uniformly as possible. You can also set `N` to a vector,
// in which case len(N) must equal len(list) and the output repeats the ith entry N[i] times.
// In either case, the result will be a list of length `N`. The `exact` option requires
// that the final length is exactly as requested. If you set it to `false` then the
// algorithm will favor uniformity and the output list may have a different number of
// entries due to rounding.
// .
// When applied to a path the output path is the same geometrical shape but has some vertices
// repeated. This can be useful when you need to align paths with a different number of points.
// (See also subdivide_path for a different way to do that.)
// Arguments:
// list = list whose entries will be repeated
// N = scalar total number of points desired or vector requesting N[i] copies of vertex i.
// exact = if true return exactly the requested number of points, possibly sacrificing uniformity. If false, return uniform points that may not match the number of points requested. Default: True
// Examples:
// list = [0,1,2,3];
// echo(repeat_entries(list, 6)); // Outputs [0,0,1,2,2,3]
// echo(repeat_entries(list, 6, exact=false)); // Outputs [0,0,1,1,2,2,3,3]
// echo(repeat_entries(list, [1,1,2,1], exact=false)); // Outputs [0,1,2,2,3]
function repeat_entries(list, N, exact = true) =
assert(is_list(list) && len(list)>0, "The list cannot be void.")
assert((is_finite(N) && N>0) || is_vector(N,len(list)),
"Parameter N must be a number greater than zero or vector with the same length of `list`")
let(
length = len(list),
reps_guess = is_list(N)? N : repeat(N/length,length),
reps = exact ?
_sum_preserving_round(reps_guess)
: [for (val=reps_guess) round(val)]
)
[for(i=[0:length-1]) each repeat(list[i],reps[i])];
// Function: list_set()
// Usage:
// list_set(list, indices, values, [dflt], [minlen])
// Description:
// Takes the input list and returns a new list such that `list[indices[i]] = values[i]` for all of
// the (index,value) pairs supplied and unchanged for other indices. If you supply `indices` that are
// beyond the length of the list then the list is extended and filled in with the `dflt` value.
// If you set `minlen` then the list is lengthed, if necessary, by padding with `dflt` to that length.
// Repetitions in `indices` are not allowed. The lists `indices` and `values` must have the same length.
// If `indices` is given as a scalar, then that index of the given `list` will be set to the scalar value of `values`.
// Arguments:
// list = List to set items in. Default: []
// indices = List of indices into `list` to set.
// values = List of values to set.
// dflt = Default value to store in sparse skipped indices.
// minlen = Minimum length to expand list to.
// Examples:
// list_set([2,3,4,5], 2, 21); // Returns: [2,3,21,5]
// list_set([2,3,4,5], [1,3], [81,47]); // Returns: [2,81,4,47]
function list_set(list=[],indices,values,dflt=0,minlen=0) =
assert(is_list(list))
!is_list(indices)? (
(is_finite(indices) && indices<len(list))?
concat([for (i=idx(list)) i==indices? values : list[i]], repeat(dflt, minlen-len(list)))
: list_set(list,[indices],[values],dflt) )
:indices==[] && values==[] ?
concat(list, repeat(dflt, minlen-len(list)))
:assert(is_vector(indices) && is_list(values) && len(values)==len(indices) ,
"Index list and value list must have the same length")
let( midx = max(len(list)-1, max(indices)) )
[ for(i=[0:midx] )
let( j = search(i,indices,0),
k = j[0] )
assert( len(j)<2, "Repeated indices are not allowed." )
k!=undef ? values[k] :
i<len(list) ? list[i]:
dflt ,
each repeat(dflt, minlen-max(len(list),max(indices)))
];
// Function: list_insert()
// Usage:
// list_insert(list, indices, values);
// Description:
// Insert `values` into `list` before position `indices`.
// Example:
// list_insert([3,6,9,12],1,5); // Returns [3,5,6,9,12]
// list_insert([3,6,9,12],[1,3],[5,11]); // Returns [3,5,6,9,11,12]
function list_insert(list, indices, values) =
assert(is_list(list))
!is_list(indices)?
assert( is_finite(indices) && is_finite(values), "Invalid indices/values." )
assert( indices<=len(list), "Indices must be <= len(list) ." )
[
for (i=idx(list)) each ( i==indices? [ values, list[i] ] : [ list[i] ] ),
if (indices==len(list)) values
]
: indices==[] && values==[] ? list
: assert( is_vector(indices) && is_list(values) && len(values)==len(indices) ,
"Index list and value list must have the same length")
assert( max(indices)<=len(list), "Indices must be <= len(list) ." )
let( maxidx = max(indices),
minidx = min(indices) )
[ for(i=[0:1:minidx-1] ) list[i],
for(i=[minidx: min(maxidx, len(list)-1)] )
let( j = search(i,indices,0),
k = j[0],
x = assert( len(j)<2, "Repeated indices are not allowed." )
)
each ( k != undef ? [ values[k], list[i] ] : [ list[i] ] ),
for(i=[min(maxidx, len(list)-1)+1:1:len(list)-1] ) list[i],
if(maxidx==len(list)) values[max_index(indices)]
];
// Function: list_remove()
// Usage:
// list_remove(list, indices)
// Description:
// Remove all items from `list` whose indexes are in `indices`.
// Arguments:
// list = The list to remove items from.
// indices = The list of indexes of items to remove.
// Example:
// list_insert([3,6,9,12],1); // Returns: [3,9,12]
// list_insert([3,6,9,12],[1,3]); // Returns: [3,9]
function list_remove(list, indices) =
assert(is_list(list))
is_finite(indices) ?
[
for (i=[0:1:min(indices, len(list)-1)-1]) list[i],
for (i=[min(indices, len(list)-1)+1:1:len(list)-1]) list[i]
]
: indices==[] ? list
: assert( is_vector(indices), "Invalid list `indices`." )
[
for(i=[0:len(list)-1])
if ( []==search(i,indices,1) )
list[i]
];
// Function: list_remove_values()
// Usage:
// list_remove_values(list,values,all=false) =
// Description:
// Removes the first, or all instances of the given `values` from the `list`.
// Returns the modified list.
// Arguments:
// list = The list to modify.
// values = The values to remove from the list.
// all = If true, remove all instances of the value `value` from the list `list`. If false, remove only the first. Default: false
// Example:
// animals = ["bat", "cat", "rat", "dog", "bat", "rat"];
// animals2 = list_remove_values(animals, "rat"); // Returns: ["bat","cat","dog","bat","rat"]
// nonflying = list_remove_values(animals, "bat", all=true); // Returns: ["cat","rat","dog","rat"]
// animals3 = list_remove_values(animals, ["bat","rat"]); // Returns: ["cat","dog","bat","rat"]
// domestic = list_remove_values(animals, ["bat","rat"], all=true); // Returns: ["cat","dog"]
// animals4 = list_remove_values(animals, ["tucan","rat"], all=true); // Returns: ["bat","cat","dog","bat"]
function list_remove_values(list,values=[],all=false) =
assert(is_list(list))
!is_list(values)? list_remove_values(list, values=[values], all=all) :
let(
idxs = all? flatten(search(values,list,0)) : search(values,list,1),
uidxs = unique(idxs)
) list_remove(list,uidxs);
// Function: bselect()
// Usage:
// bselect(array,index);
// Description:
// Returns the items in `array` whose matching element in `index` is true.
// Arguments:
// array = Initial list to extract items from.
// index = List of booleans.
// Example:
// bselect([3,4,5,6,7], [false,true,true,false,true]); // Returns: [4,5,7]
function bselect(array,index) =
assert(is_list(array)||is_string(array), "Improper array." )
assert(is_list(index) && len(index)>=len(array) , "Improper index list." )
is_string(array)? str_join(bselect( [for (x=array) x], index)) :
[for(i=[0:len(array)-1]) if (index[i]) array[i]];
// Function: list_bset()
// Usage:
// list_bset(indexset, valuelist,[dflt])
// Description:
// Opposite of `bselect()`. Returns a list the same length as `indexlist`, where each item will
// either be 0 if the corresponding item in `indexset` is false, or the next sequential value
// from `valuelist` if the item is true. The number of `true` values in `indexset` must be equal
// to the length of `valuelist`.
// Arguments:
// indexset = A list of boolean values.
// valuelist = The list of values to set into the returned list.
// dflt = Default value to store when the indexset item is false.
// Example:
// list_bset([false,true,false,true,false], [3,4]); // Returns: [0,3,0,4,0]
// list_bset([false,true,false,true,false], [3,4],dflt=1); // Returns: [1,3,1,4,1]
function list_bset(indexset, valuelist, dflt=0) =
assert(is_list(indexset), "The index set is not a list." )
assert(is_list(valuelist), "The `valuelist` is not a list." )
let( trueind = search([true], indexset,0)[0] )
assert( !(len(trueind)>len(valuelist)), str("List `valuelist` too short; its length should be ",len(trueind)) )
assert( !(len(trueind)<len(valuelist)), str("List `valuelist` too long; its length should be ",len(trueind)) )
concat(
list_set([],trueind, valuelist, dflt=dflt), // Fill in all of the values
repeat(dflt,len(indexset)-max(trueind)-1) // Add trailing values so length matches indexset
);
// Section: List Length Manipulation
// Function: list_shortest()
// Description:
// Returns the length of the shortest sublist in a list of lists.
// Arguments:
// array = A list of lists.
function list_shortest(array) =
assert(is_list(array), "Invalid input." )
min([for (v = array) len(v)]);
// Function: list_longest()
// Description:
// Returns the length of the longest sublist in a list of lists.
// Arguments:
// array = A list of lists.
function list_longest(array) =
assert(is_list(array), "Invalid input." )
max([for (v = array) len(v)]);
// Function: list_pad()
// Description:
// If the list `array` is shorter than `minlen` length, pad it to length with the value given in `fill`.
// Arguments:
// array = A list.
// minlen = The minimum length to pad the list to.
// fill = The value to pad the list with.
function list_pad(array, minlen, fill=undef) =
assert(is_list(array), "Invalid input." )
concat(array,repeat(fill,minlen-len(array)));
// Function: list_trim()
// Description:
// If the list `array` is longer than `maxlen` length, truncates it to be `maxlen` items long.
// Arguments:
// array = A list.
// minlen = The minimum length to pad the list to.
function list_trim(array, maxlen) =
assert(is_list(array), "Invalid input." )
[for (i=[0:1:min(len(array),maxlen)-1]) array[i]];
// Function: list_fit()
// Description:
// If the list `array` is longer than `length` items long, truncates it to be exactly `length` items long.
// If the list `array` is shorter than `length` items long, pad it to length with the value given in `fill`.
// Arguments:
// array = A list.
// minlen = The minimum length to pad the list to.
// fill = The value to pad the list with.
function list_fit(array, length, fill) =
assert(is_list(array), "Invalid input." )
let(l=len(array))
l==length ? array :
l> length ? list_trim(array,length)
: list_pad(array,length,fill);
// Section: List Shuffling and Sorting
// returns true for valid index specifications idx in the interval [imin, imax)
// note that idx can't have any value greater or EQUAL to imax
// this allows imax=INF as a bound to numerical lists
function _valid_idx(idx,imin,imax) =
is_undef(idx)
|| ( is_finite(idx)
&& ( is_undef(imin) || idx>=imin )
&& ( is_undef(imax) || idx< imax ) )
|| ( is_list(idx)
&& ( is_undef(imin) || min(idx)>=imin )
&& ( is_undef(imax) || max(idx)< imax ) )
|| ( is_range(idx)
&& ( is_undef(imin) || (idx[1]>0 && idx[0]>=imin ) || (idx[1]<0 && idx[0]<=imax ) )
&& ( is_undef(imax) || (idx[1]>0 && idx[2]<=imax ) || (idx[1]<0 && idx[2]>=imin ) ) );
// Function: shuffle()
// Usage:
// shuffled = shuffle(list,[seed])
// Description:
// Shuffles the input list into random order.
// If given a string, shuffles the characters within the string.
// If you give a numeric seed value then the permutation
// will be repeatable.
function shuffle(list,seed) =
assert(is_list(list)||is_string(list), "Invalid input." )
is_string(list)? str_join(shuffle([for (x = list) x],seed=seed)) :
len(list)<=1 ? list :
let (
rval = is_num(seed) ? rands(0,1,len(list),seed_value=seed)
: rands(0,1,len(list)),
left = [for (i=[0:len(list)-1]) if (rval[i]< 0.5) list[i]],
right = [for (i=[0:len(list)-1]) if (rval[i]>=0.5) list[i]]
)
concat(shuffle(left), shuffle(right));
// Sort a vector of scalar values with the native comparison operator
// all elements should have the same type.
function _sort_scalars(arr) =
len(arr)<=1 ? arr :
let(
pivot = arr[floor(len(arr)/2)],
lesser = [ for (y = arr) if (y < pivot) y ],
equal = [ for (y = arr) if (y == pivot) y ],
greater = [ for (y = arr) if (y > pivot) y ]
)
concat( _sort_scalars(lesser), equal, _sort_scalars(greater) );
// lexical sort of a homogeneous list of vectors
// uses native comparison operator
function _sort_vectors(arr, _i=0) =
len(arr)<=1 || _i>=len(arr[0]) ? arr :
let(
pivot = arr[floor(len(arr)/2)][_i],
lesser = [ for (entry=arr) if (entry[_i] < pivot ) entry ],
equal = [ for (entry=arr) if (entry[_i] == pivot ) entry ],
greater = [ for (entry=arr) if (entry[_i] > pivot ) entry ]
)
concat(
_sort_vectors(lesser, _i ),
_sort_vectors(equal, _i+1 ),
_sort_vectors(greater, _i ) );
// lexical sort of a homogeneous list of vectors by the vector components with indices in idxlist
// all idxlist indices should be in the range of the vector dimensions
// idxlist must be undef or a simple list of numbers
// uses native comparison operator
function _sort_vectors(arr, idxlist, _i=0) =
len(arr)<=1 || ( is_list(idxlist) && _i>=len(idxlist) ) || _i>=len(arr[0]) ? arr :
let(
k = is_list(idxlist) ? idxlist[_i] : _i,
pivot = arr[floor(len(arr)/2)][k],
lesser = [ for (entry=arr) if (entry[k] < pivot ) entry ],
equal = [ for (entry=arr) if (entry[k] == pivot ) entry ],
greater = [ for (entry=arr) if (entry[k] > pivot ) entry ]
)
concat(
_sort_vectors(lesser, idxlist, _i ),
_sort_vectors(equal, idxlist, _i+1),
_sort_vectors(greater, idxlist, _i ) );
// sorting using compare_vals(); returns indexed list when `indexed==true`
function _sort_general(arr, idx=undef, indexed=false) =
(len(arr)<=1) ? arr :
! indexed && is_undef(idx)
? _lexical_sort(arr)
: let( arrind = _indexed_sort(enumerate(arr,idx)) )
indexed
? arrind
: [for(i=arrind) arr[i]];
// lexical sort using compare_vals()
function _lexical_sort(arr) =
arr==[] ? [] : len(arr)==1? arr :
let( pivot = arr[floor(len(arr)/2)] )
let(
lesser = [ for (entry=arr) if (compare_vals(entry, pivot) <0 ) entry ],
equal = [ for (entry=arr) if (compare_vals(entry, pivot)==0 ) entry ],
greater = [ for (entry=arr) if (compare_vals(entry, pivot) >0 ) entry ]
)
concat(_lexical_sort(lesser), equal, _lexical_sort(greater));
// given a list of pairs, return the first element of each pair of the list sorted by the second element of the pair
// the sorting is done using compare_vals()
function _indexed_sort(arrind) =
arrind==[] ? [] : len(arrind)==1? [arrind[0][0]] :
let( pivot = arrind[floor(len(arrind)/2)][1] )
let(
lesser = [ for (entry=arrind) if (compare_vals(entry[1], pivot) <0 ) entry ],
equal = [ for (entry=arrind) if (compare_vals(entry[1], pivot)==0 ) entry[0] ],
greater = [ for (entry=arrind) if (compare_vals(entry[1], pivot) >0 ) entry ]
)
concat(_indexed_sort(lesser), equal, _indexed_sort(greater));
// Function: sort()
// Usage:
// sort(list, [idx])
// Description:
// Sorts the given list in lexicographic order. If the input is a homogeneous simple list or a homogeneous
// list of vectors (see function is_homogeneous), the sorting method uses the native comparison operator and is faster.
// When sorting non homogeneous list the elements are compared with `compare_vals`, with types ordered according to
// `undef < boolean < number < string < list`. Comparison of lists is recursive.
// When comparing vectors, homogeneous or not, the parameter `idx` may be used to select the components to compare.
// Note that homogeneous lists of vectors may contain mixed types provided that for any two list elements
// list[i] and list[j] satisfies type(list[i][k])==type(list[j][k]) for all k.
// Strings are allowed as any list element and are compared with the native operators although no substring
// comparison is possible.
// Arguments:
// list = The list to sort.
// idx = If given, do the comparison based just on the specified index, range or list of indices.
// Example:
// // Homogeneous lists
// l1 = [45,2,16,37,8,3,9,23,89,12,34];
// sorted1 = sort(l1); // Returns [2,3,8,9,12,16,23,34,37,45,89]
// l2 = [["oat",0], ["cat",1], ["bat",3], ["bat",2], ["fat",3]];
// sorted2 = sort(l2); // Returns: [["bat",2],["bat",3],["cat",1],["fat",3],["oat",0]]
// // Non-homegenous list
// l3 = [[4,0],[7],[3,9],20,[4],[3,1],[8]];
// sorted3 = sort(l3); // Returns: [20,[3,1],[3,9],[4],[4,0],[7],[8]]
function sort(list, idx=undef) =
assert(is_list(list)||is_string(list), "Invalid input." )
is_string(list)? str_join(sort([for (x = list) x],idx)) :
!is_list(list) || len(list)<=1 ? list :
is_homogeneous(list,1)
? let(size = array_dim(list[0]))
size==0 ? _sort_scalars(list)
: len(size)!=1 ? _sort_general(list,idx)
: is_undef(idx) ? _sort_vectors(list)
: assert( _valid_idx(idx) , "Invalid indices.")
_sort_vectors(list,[for(i=idx) i])
: _sort_general(list,idx);
// Function: sortidx()
// Description:
// Given a list, sort it as function `sort()`, and returns
// a list of indexes into the original list in that sorted order.
// If you iterate the returned list in order, and use the list items
// to index into the original list, you will be iterating the original
// values in sorted order.
// Example:
// lst = ["d","b","e","c"];
// idxs = sortidx(lst); // Returns: [1,3,0,2]
// ordered = select(lst, idxs); // Returns: ["b", "c", "d", "e"]
// Example:
// lst = [
// ["foo", 88, [0,0,1], false],
// ["bar", 90, [0,1,0], true],
// ["baz", 89, [1,0,0], false],
// ["qux", 23, [1,1,1], true]
// ];
// idxs1 = sortidx(lst, idx=1); // Returns: [3,0,2,1]
// idxs2 = sortidx(lst, idx=0); // Returns: [1,2,0,3]
// idxs3 = sortidx(lst, idx=[1,3]); // Returns: [3,0,2,1]
function sortidx(list, idx=undef) =
assert(is_list(list)||is_string(list), "Invalid input." )
!is_list(list) || len(list)<=1 ? list :
is_homogeneous(list,1)
? let(
size = array_dim(list[0]),
aug = ! (size==0 || len(size)==1) ? 0 // for general sorting
: [for(i=[0:len(list)-1]) concat(i,list[i])], // for scalar or vector sorting
lidx = size==0? [1] : // scalar sorting
len(size)==1
? is_undef(idx) ? [for(i=[0:len(list[0])-1]) i+1] // vector sorting
: [for(i=idx) i+1] // vector sorting
: 0 // just to signal
)
assert( ! ( size==0 && is_def(idx) ),
"The specification of `idx` is incompatible with scalar sorting." )
assert( _valid_idx(idx) , "Invalid indices." )
lidx!=0
? let( lsort = _sort_vectors(aug,lidx) )
[for(li=lsort) li[0] ]
: _sort_general(list,idx,indexed=true)
: _sort_general(list,idx,indexed=true);
// Function: unique()
// Usage:
// l = unique(list);
// Description:
// Returns a sorted list with all repeated items removed.
// Arguments:
// list = The list to uniquify.
function unique(list) =
assert(is_list(list)||is_string(list), "Invalid input." )
is_string(list)? str_join(unique([for (x = list) x])) :
len(list)<=1? list :
let( sorted = sort(list))
[ for (i=[0:1:len(sorted)-1])
if (i==0 || (sorted[i] != sorted[i-1]))
sorted[i]
];
// Function: unique_count()
// Usage:
// counts = unique_count(list);
// Description:
// Returns `[sorted,counts]` where `sorted` is a sorted list of the unique items in `list` and `counts` is a list such
// that `count[i]` gives the number of times that `sorted[i]` appears in `list`.
// Arguments:
// list = The list to analyze.
function unique_count(list) =
assert(is_list(list) || is_string(list), "Invalid input." )
list == [] ? [[],[]] :
let( list=sort(list) )
let( ind = [0, for(i=[1:1:len(list)-1]) if (list[i]!=list[i-1]) i] )
[ select(list,ind), deltas( concat(ind,[len(list)]) ) ];
// Section: List Iteration Helpers
// Function: idx()
// Usage:
// i = idx(list);
// for(i=idx(list)) ...
// Description:
// Returns the range of indexes for the given list.
// Arguments:
// list = The list to returns the index range of.
// step = The step size to stride through the list. Default: 1
// end = The delta from the end of the list. Default: -1
// start = The starting index. Default: 0
// Example(2D):
// colors = ["red", "green", "blue"];
// for (i=idx(colors)) right(20*i) color(colors[i]) circle(d=10);
function idx(list, step=1, end=-1,start=0) =
assert(is_list(list)||is_string(list), "Invalid input." )
[start : step : len(list)+end];
// Function: enumerate()
// Description:
// Returns a list, with each item of the given list `l` numbered in a sublist.
// Something like: `[[0,l[0]], [1,l[1]], [2,l[2]], ...]`
// Arguments:
// l = List to enumerate.
// idx = If given, enumerates just the given subindex items of `l`.
// Example:
// enumerate(["a","b","c"]); // Returns: [[0,"a"], [1,"b"], [2,"c"]]
// enumerate([[88,"a"],[76,"b"],[21,"c"]], idx=1); // Returns: [[0,"a"], [1,"b"], [2,"c"]]
// enumerate([["cat","a",12],["dog","b",10],["log","c",14]], idx=[1:2]); // Returns: [[0,"a",12], [1,"b",10], [2,"c",14]]
// Example(2D):
// colors = ["red", "green", "blue"];
// for (p=enumerate(colors)) right(20*p[0]) color(p[1]) circle(d=10);
function enumerate(l,idx=undef) =
assert(is_list(l)||is_string(list), "Invalid input." )
assert( _valid_idx(idx,0,len(l)), "Invalid index/indices." )
(idx==undef)
? [for (i=[0:1:len(l)-1]) [i,l[i]]]
: [for (i=[0:1:len(l)-1]) [ i, for (j=idx) l[i][j]] ];
// Function: force_list()
// Usage:
// list = force_list(value, [n], [fill])
// Description:
// Coerces non-list values into a list. Makes it easy to treat a scalar input
// consistently as a singleton list, as well as list inputs.
// - If `value` is a list, then that list is returned verbatim.
// - If `value` is not a list, and `fill` is not given, then a list of `n` copies of `value` will be returned.
// - If `value` is not a list, and `fill` is given, then a list `n` items long will be returned where `value` will be the first item, and the rest will contain the value of `fill`.
// Arguments:
// value = The value or list to coerce into a list.
// n = The number of items in the coerced list. Default: 1
// fill = The value to pad the coerced list with, after the firt value. Default: undef (pad with copies of `value`)
// Examples:
// x = force_list([3,4,5]); // Returns: [3,4,5]
// y = force_list(5); // Returns: [5]
// z = force_list(7, n=3); // Returns: [7,7,7]
// w = force_list(4, n=3, fill=1); // Returns: [4,1,1]
function force_list(value, n=1, fill) =
is_list(value) ? value :
is_undef(fill)? [for (i=[1:1:n]) value] : [value, for (i=[2:1:n]) fill];
// Function: pair()
// Usage:
// pair(v)
// Description:
// Takes a list, and returns a list of adjacent pairs from it.
// Example(2D): Note that the last point and first point do NOT get paired together.
// for (p = pair(circle(d=20, $fn=12)))
// move(p[0])
// rot(from=BACK, to=p[1]-p[0])
// trapezoid(w1=1, w2=0, h=norm(p[1]-p[0]), anchor=FRONT);
// Example:
// l = ["A","B","C","D"];
// echo([for (p=pair(l)) str(p.y,p.x)]); // Outputs: ["BA", "CB", "DC"]
function pair(v) =
assert(is_list(v)||is_string(v), "Invalid input." )
[for (i=[0:1:len(v)-2]) [v[i],v[i+1]]];
// Function: pair_wrap()
// Usage:
// pair_wrap(v)
// Description:
// Takes a list, and returns a list of adjacent pairs from it, wrapping around from the end to the start of the list.
// Example(2D):
// for (p = pair_wrap(circle(d=20, $fn=12)))
// move(p[0])
// rot(from=BACK, to=p[1]-p[0])
// trapezoid(w1=1, w2=0, h=norm(p[1]-p[0]), anchor=FRONT);
// Example:
// l = ["A","B","C","D"];
// echo([for (p=pair_wrap(l)) str(p.y,p.x)]); // Outputs: ["BA", "CB", "DC", "AD"]
function pair_wrap(v) =
assert(is_list(v)||is_string(v), "Invalid input." )
[for (i=[0:1:len(v)-1]) [v[i],v[(i+1)%len(v)]]];
// Function: triplet()
// Usage:
// triplet(v)
// Description:
// Takes a list, and returns a list of adjacent triplets from it.
// Example:
// l = ["A","B","C","D","E"];
// echo([for (p=triplet(l)) str(p.z,p.y,p.x)]); // Outputs: ["CBA", "DCB", "EDC"]
function triplet(v) =
assert(is_list(v)||is_string(v), "Invalid input." )
[for (i=[0:1:len(v)-3]) [v[i],v[i+1],v[i+2]]];
// Function: triplet_wrap()
// Usage:
// triplet_wrap(v)
// Description:
// Takes a list, and returns a list of adjacent triplets from it, wrapping around from the end to the start of the list.
// Example:
// l = ["A","B","C","D"];
// echo([for (p=triplet_wrap(l)) str(p.z,p.y,p.x)]); // Outputs: ["CBA", "DCB", "ADC", "BAD"]
function triplet_wrap(v) =
assert(is_list(v)||is_string(v), "Invalid input." )
[for (i=[0:1:len(v)-1]) [v[i],v[(i+1)%len(v)],v[(i+2)%len(v)]]];
// Function: permute()
// Usage:
// list = permute(l, [n]);
// Description:
// Returns an ordered list of every unique permutation of `n` items out of the given list `l`.
// For the list `[1,2,3,4]`, with `n=2`, this will return `[[1,2], [1,3], [1,4], [2,3], [2,4], [3,4]]`.
// For the list `[1,2,3,4]`, with `n=3`, this will return `[[1,2,3], [1,2,4], [1,3,4], [2,3,4]]`.
// Arguments:
// l = The list to provide permutations for.
// n = The number of items in each permutation. Default: 2
// Example:
// pairs = permute([3,4,5,6]); // Returns: [[3,4],[3,5],[3,6],[4,5],[4,6],[5,6]]
// triplets = permute([3,4,5,6],n=3); // Returns: [[3,4,5],[3,4,6],[3,5,6],[4,5,6]]
// Example(2D):
// for (p=permute(regular_ngon(n=7,d=100))) stroke(p);
function permute(l,n=2,_s=0) =
assert(is_list(l), "Invalid list." )
assert( is_finite(n) && n>=1 && n<=len(l), "Invalid number `n`." )
n==1
? [for (i=[_s:1:len(l)-1]) [l[i]]]
: [for (i=[_s:1:len(l)-n], p=permute(l,n=n-1,_s=i+1)) concat([l[i]], p)];
// Section: Set Manipulation
// Function: set_union()
// Usage:
// s = set_union(a, b, [get_indices]);
// Description:
// Given two sets (lists with unique items), returns the set of unique items that are in either `a` or `b`.
// If `get_indices` is true, a list of indices into the new union set are returned for each item in `b`,
// in addition to returning the new union set. In this case, a 2-item list is returned, `[INDICES, NEWSET]`,
// where INDICES is the list of indices for items in `b`, and NEWSET is the new union set.
// Arguments:
// a = One of the two sets to merge.
// b = The other of the two sets to merge.
// get_indices = If true, indices into the new union set are also returned for each item in `b`. Returns `[INDICES, NEWSET]`. Default: false
// Example:
// set_a = [2,3,5,7,11];
// set_b = [1,2,3,5,8];
// set_u = set_union(set_a, set_b);
// // set_u now equals [2,3,5,7,11,1,8]
// set_v = set_union(set_a, set_b, get_indices=true);
// // set_v now equals [[5,0,1,2,6], [2,3,5,7,11,1,8]]
function set_union(a, b, get_indices=false) =
assert( is_list(a) && is_list(b), "Invalid sets." )
let(
found1 = search(b, a),
found2 = search(b, b),
c = [ for (i=idx(b))
if (found1[i] == [] && found2[i] == i)
b[i]
],
nset = concat(a, c)
)
! get_indices ? nset :
let(
la = len(a),
found3 = search(b, c),
idxs = [ for (i=idx(b))
(found1[i] != [])? found1[i] : la + found3[i]
]
) [idxs, nset];
// Function: set_difference()
// Usage:
// s = set_difference(a, b);
// Description:
// Given two sets (lists with unique items), returns the set of items that are in `a`, but not `b`.
// Arguments:
// a = The starting set.
// b = The set of items to remove from set `a`.
// Example:
// set_a = [2,3,5,7,11];
// set_b = [1,2,3,5,8];
// set_d = set_difference(set_a, set_b);
// // set_d now equals [7,11]
function set_difference(a, b) =
assert( is_list(a) && is_list(b), "Invalid sets." )
let( found = search(a, b, num_returns_per_match=1) )
[ for (i=idx(a)) if(found[i]==[]) a[i] ];
// Function: set_intersection()
// Usage:
// s = set_intersection(a, b);
// Description:
// Given two sets (lists with unique items), returns the set of items that are in both sets.
// Arguments:
// a = The starting set.
// b = The set of items to intersect with set `a`.
// Example:
// set_a = [2,3,5,7,11];
// set_b = [1,2,3,5,8];
// set_i = set_intersection(set_a, set_b);
// // set_i now equals [2,3,5]
function set_intersection(a, b) =
assert( is_list(a) && is_list(b), "Invalid sets." )
let( found = search(a, b, num_returns_per_match=1) )
[ for (i=idx(a)) if(found[i]!=[]) a[i] ];
// Section: Array Manipulation
// Function: add_scalar()
// Usage:
// add_scalar(v,s);
// Description:
// Given an array and a scalar, returns the array with the scalar added to each item in it.
// If given a list of arrays, recursively adds the scalar to the each array.
// Arguments:
// v = The initial array.
// s = A scalar value to add to every item in the array.
// Example:
// add_scalar([1,2,3],3); // Returns: [4,5,6]
// add_scalar([[1,2,3],[3,4,5]],3); // Returns: [[4,5,6],[6,7,8]]
function add_scalar(v,s) =
is_finite(s) ? [for (x=v) is_list(x)? add_scalar(x,s) : is_finite(x) ? x+s: x] : v;
// Function: subindex()
// Usage:
// subindex(M, idx)
// Description:
// Extracts the entries listed in idx from each entry in M. For a matrix this means
// selecting a specified set of columns. If idx is a number the return is a vector,
// otherwise it is a list of lists (the submatrix).
// This function will return `undef` at all entry positions indexed by idx not found in the input list M.
// Arguments:
// M = The given list of lists.
// idx = The index, list of indices, or range of indices to fetch.
// Example:
// M = [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16]];
// subindex(M,2); // Returns [3, 7, 11, 15]
// subindex(M,[2]); // Returns [[3], [7], [11], [15]]
// subindex(M,[2,1]); // Returns [[3, 2], [7, 6], [11, 10], [15, 14]]
// subindex(M,[1:3]); // Returns [[2, 3, 4], [6, 7, 8], [10, 11, 12], [14, 15, 16]]
// N = [ [1,2], [3], [4,5], [6,7,8] ];
// subindex(N,[0,1]); // Returns [ [1,2], [3,undef], [4,5], [6,7] ]
function subindex(M, idx) =
assert( is_list(M), "The input is not a list." )
assert( !is_undef(idx) && _valid_idx(idx,0,1/0), "Invalid index input." )
is_finite(idx)
? [for(row=M) row[idx]]
: [for(row=M) [for(i=idx) row[i]]];
// Function: submatrix()
// Usage:
// mat = submatrix(M, idx1, idx2)
// Description:
// The input must be a list of lists (a matrix or 2d array). Returns a submatrix by selecting the rows listed in idx1 and columns listed in idx2.
// Arguments:
// M = Given list of lists
// idx1 = rows index list or range
// idx2 = column index list or range
// Example:
// M = [[ 1, 2, 3, 4, 5],
// [ 6, 7, 8, 9,10],
// [11,12,13,14,15],
// [16,17,18,19,20],
// [21,22,23,24,25]];
// submatrix(M,[1:2],[3:4]); // Returns [[9, 10], [14, 15]]
// submatrix(M,[1], [3,4])); // Returns [[9,10]]
// submatrix(M,1, [3,4])); // Returns [[9,10]]
// submatrix(M,1,3)); // Returns [[9]]
// submatrix(M, [3,4],1); // Returns [[17],[22]]);
// submatrix(M, [1,3],[2,4]); // Returns [[8,10],[18,20]]);
// A = [[true, 17, "test"],
// [[4,2], 91, false],
// [6, [3,4], undef]];
// submatrix(A,[0,2],[1,2]); // Returns [[17, "test"], [[3, 4], undef]]
function submatrix(M,idx1,idx2) =
[for(i=idx1) [for(j=idx2) M[i][j] ] ];
// Function: zip()
// Usage:
// zip(v1, v2, v3, [fit], [fill]);
// zip(vecs, [fit], [fill]);
// Description:
// Zips together corresponding items from two or more lists.
// Returns a list of lists, where each sublist contains corresponding
// items from each of the input lists. `[[A1, B1, C1], [A2, B2, C2], ...]`
// Arguments:
// vecs = A list of two or more lists to zipper together.
// fit = If `fit=="short"`, the zips together up to the length of the shortest list in vecs. If `fit=="long"`, then pads all lists to the length of the longest, using the value in `fill`. If `fit==false`, then requires all lists to be the same length. Default: false.
// fill = The default value to fill in with if one or more lists if short. Default: undef
// Example:
// v1 = [1,2,3,4];
// v2 = [5,6,7];
// v3 = [8,9,10,11];
// zip(v1,v3); // returns [[1,8], [2,9], [3,10], [4,11]]
// zip([v1,v3]); // returns [[1,8], [2,9], [3,10], [4,11]]
// zip([v1,v2], fit="short"); // returns [[1,5], [2,6], [3,7]]
// zip([v1,v2], fit="long"); // returns [[1,5], [2,6], [3,7], [4,undef]]
// zip([v1,v2], fit="long, fill=0); // returns [[1,5], [2,6], [3,7], [4,0]]
// zip([v1,v2,v3], fit="long"); // returns [[1,5,8], [2,6,9], [3,7,10], [4,undef,11]]
// Example:
// v1 = [[1,2,3], [4,5,6], [7,8,9]];
// v2 = [[20,19,18], [17,16,15], [14,13,12]];
// zip(v1,v2); // Returns [[1,2,3,20,19,18], [4,5,6,17,16,15], [7,8,9,14,13,12]]
function zip(vecs, v2, v3, fit=false, fill=undef) =
(v3!=undef)? zip([vecs,v2,v3], fit=fit, fill=fill) :
(v2!=undef)? zip([vecs,v2], fit=fit, fill=fill) :
assert(in_list(fit, [false, "short", "long"]), "Invalid fit value." )
assert(all([for(v=vecs) is_list(v)]), "One of the inputs to zip is not a list")
let(
minlen = list_shortest(vecs),
maxlen = list_longest(vecs)
)
assert(fit!=false || minlen==maxlen, "Input vectors to zip must have the same length")
(fit == "long")
? [for(i=[0:1:maxlen-1]) [for(v=vecs) for(x=(i<len(v)? v[i] : (fill==undef)? [fill] : fill)) x] ]
: [for(i=[0:1:minlen-1]) [for(v=vecs) for(x=v[i]) x] ];
// Function: block_matrix()
// Usage:
// block_matrix([[M11, M12,...],[M21, M22,...], ... ])
// Description:
// Create a block matrix by supplying a matrix of matrices, which will
// be combined into one unified matrix. Every matrix in one row
// must have the same height, and the combined width of the matrices
// in each row must be equal.
function block_matrix(M) =
let(
bigM = [for(bigrow = M) each zip(bigrow)],
len0=len(bigM[0]),
badrows = [for(row=bigM) if (len(row)!=len0) 1]
)
assert(badrows==[], "Inconsistent or invalid input")
bigM;
// Function: diagonal_matrix()
// Usage:
// diagonal_matrix(diag, [offdiag])
// Description:
// Creates a square matrix with the items in the list `diag` on
// its diagonal. The off diagonal entries are set to offdiag,
// which is zero by default.
function diagonal_matrix(diag,offdiag=0) =
assert(is_list(diag) && len(diag)>0)
[for(i=[0:1:len(diag)-1]) [for(j=[0:len(diag)-1]) i==j?diag[i] : offdiag]];
// Function: submatrix_set()
// Usage:
// mat = submatrix_set(M,A,[m],[n])
// Description:
// Sets a submatrix of M equal to the matrix A. By default the top left corner of M is set to A, but
// you can specify offset coordinates m and n. If A (as adjusted by m and n) extends beyond the bounds
// of M then the extra entries are ignored. You can pass in A=[[]], a null matrix, and M will be
// returned unchanged. Note that the input M need not be rectangular in shape.
function submatrix_set(M,A,m=0,n=0) =
assert(is_list(M))
assert(is_list(A))
assert(is_int(m))
assert(is_int(n))
let( badrows = [for(i=idx(A)) if (!is_list(A[i])) i])
assert(badrows==[], str("Input submatrix malformed rows: ",badrows))
[for(i=[0:1:len(M)-1])
assert(is_list(M[i]), str("Row ",i," of input matrix is not a list"))
[for(j=[0:1:len(M[i])-1])
i>=m && i <len(A)+m && j>=n && j<len(A[0])+n ? A[i-m][j-n] : M[i][j]]];
// Function: array_group()
// Description:
// Takes a flat array of values, and groups items in sets of `cnt` length.
// The opposite of this is `flatten()`.
// Arguments:
// v = The list of items to group.
// cnt = The number of items to put in each grouping.
// dflt = The default value to fill in with is the list is not a multiple of `cnt` items long.
// Example:
// v = [1,2,3,4,5,6];
// array_group(v,2) returns [[1,2], [3,4], [5,6]]
// array_group(v,3) returns [[1,2,3], [4,5,6]]
// array_group(v,4,0) returns [[1,2,3,4], [5,6,0,0]]
function array_group(v, cnt=2, dflt=0) = [for (i = [0:cnt:len(v)-1]) [for (j = [0:1:cnt-1]) default(v[i+j], dflt)]];
// Function: flatten()
// Description: Takes a list of lists and flattens it by one level.
// Arguments:
// l = List to flatten.
// Example:
// flatten([[1,2,3], [4,5,[6,7,8]]]) returns [1,2,3,4,5,[6,7,8]]
function flatten(l) = [for (a = l) each a];
// Function: full_flatten()
// Description:
// Collects in a list all elements recursively found in any level of the given list.
// The output list is ordered in depth first order.
// Arguments:
// l = List to flatten.
// Example:
// full_flatten([[1,2,3], [4,5,[6,7,8]]]) returns [1,2,3,4,5,6,7,8]
function full_flatten(l) = [for(a=l) if(is_list(a)) (each full_flatten(a)) else a ];
// Internal. Not exposed.
function _array_dim_recurse(v) =
!is_list(v[0])
? len( [for(entry=v) if(!is_list(entry)) 0] ) == 0 ? [] : [undef]
: let(
firstlen = is_list(v[0]) ? len(v[0]): undef,
first = len( [for(entry = v) if(! is_list(entry) || (len(entry) != firstlen)) 0 ] ) == 0 ? firstlen : undef,
leveldown = flatten(v)
)
is_list(leveldown[0])
? concat([first],_array_dim_recurse(leveldown))
: [first];
function _array_dim_recurse(v) =
let( alen = [for(vi=v) is_list(vi) ? len(vi): -1] )
v==[] || max(alen)==-1 ? [] :
let( add = max(alen)!=min(alen) ? undef : alen[0] )
concat( add, _array_dim_recurse(flatten(v)));
// Function: array_dim()
// Usage:
// array_dim(v, [depth])
// Description:
// Returns the size of a multi-dimensional array. Returns a list of
// dimension lengths. The length of `v` is the dimension `0`. The
// length of the items in `v` is dimension `1`. The length of the
// items in the items in `v` is dimension `2`, etc. For each dimension,
// if the length of items at that depth is inconsistent, `undef` will
// be returned. If no items of that dimension depth exist, `0` is
// returned. Otherwise, the consistent length of items in that
// dimensional depth is returned.
// Arguments:
// v = Array to get dimensions of.
// depth = Dimension to get size of. If not given, returns a list of dimension lengths.
// Examples:
// array_dim([[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]]); // Returns [2,2,3]
// array_dim([[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]], 0); // Returns 2
// array_dim([[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]], 2); // Returns 3
// array_dim([[[1,2,3],[4,5,6]],[[7,8,9]]]); // Returns [2,undef,3]
function array_dim(v, depth=undef) =
assert( is_undef(depth) || ( is_finite(depth) && depth>=0 ), "Invalid depth.")
! is_list(v) ? 0 :
(depth == undef)
? concat([len(v)], _array_dim_recurse(v))
: (depth == 0)
? len(v)
: let( dimlist = _array_dim_recurse(v))
(depth > len(dimlist))? 0 : dimlist[depth-1] ;
// Function: transpose()
// Usage:
// transpose(arr, [reverse])
// Description:
// Returns the transpose of the given input array. The input should be a list of lists that are
// all the same length. If you give a vector then transpose returns it unchanged.
// When reverse=true, the transpose is done across to the secondary diagonal. (See example below.)
// By default, reverse=false.
// Example:
// arr = [
// ["a", "b", "c"],
// ["d", "e", "f"],
// ["g", "h", "i"]
// ];
// t = transpose(arr);
// // Returns:
// // [
// // ["a", "d", "g"],
// // ["b", "e", "h"],
// // ["c", "f", "i"],
// // ]
// Example:
// arr = [
// ["a", "b", "c"],
// ["d", "e", "f"]
// ];
// t = transpose(arr);
// // Returns:
// // [
// // ["a", "d"],
// // ["b", "e"],
// // ["c", "f"],
// // ]
// Example:
// arr = [
// ["a", "b", "c"],
// ["d", "e", "f"],
// ["g", "h", "i"]
// ];
// t = transpose(arr, reverse=true);
// // Returns:
// // [
// // ["i", "f", "c"],
// // ["h", "e", "b"],
// // ["g", "d", "a"]
// // ]
// Example: Transpose on a list of numbers returns the list unchanged
// transpose([3,4,5]); // Returns: [3,4,5]
function transpose(arr, reverse=false) =
assert( is_list(arr) && len(arr)>0, "Input to transpose must be a nonempty list.")
is_list(arr[0])
? let( len0 = len(arr[0]) )
assert([for(a=arr) if(!is_list(a) || len(a)!=len0) 1 ]==[], "Input to transpose has inconsistent row lengths." )
reverse
? [for (i=[0:1:len0-1])
[ for (j=[0:1:len(arr)-1]) arr[len(arr)-1-j][len0-1-i] ] ]
: [for (i=[0:1:len0-1])
[ for (j=[0:1:len(arr)-1]) arr[j][i] ] ]
: assert( is_vector(arr), "Input to transpose must be a vector or list of lists.")
arr;
// vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap
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