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Added python-style zip(), zip_long(), combinations() and permutations().

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This commit is contained in:
Garth Minette 2021-03-10 14:49:39 -08:00
parent 50bd361119
commit 5b22e6f2d9
2 changed files with 98 additions and 19 deletions
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109
arrays.scad
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@ -41,7 +41,7 @@ function is_homogeneous(l, depth=10) =
[] == [for(i=[1:len(l)-1]) if( ! _same_type(l[i],l0, depth+1) ) 0 ];
function is_homogenous(l, depth=10) = is_homogeneous(l, depth);
function _same_type(a,b, depth) =
(depth==0) ||
(is_undef(a) && is_undef(b)) ||
@ -50,7 +50,7 @@ function _same_type(a,b, depth) =
(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:
@ -1084,7 +1084,7 @@ function unique_count(list) =
// rng = idx(list, <s=>, <e=>, <step=>);
// for(i=idx(list, <s=>, <e=>, <step=>)) ...
// Topics: List Handling, Iteration
// See Also: enumerate(), pair(), triplet(), permute()
// See Also: enumerate(), pair(), triplet(), combinations(), permutations()
// Description:
// Returns the range of indexes for the given list.
// Arguments:
@ -1110,7 +1110,7 @@ function idx(list, s=0, e=-1, step=1) =
// arr = enumerate(l, <idx>);
// for (x = enumerate(l, <idx>)) ... // x[0] is the index number, x[1] is the item.
// Topics: List Handling, Iteration
// See Also: idx(), pair(), triplet(), permute()
// See Also: idx(), pair(), triplet(), combinations(), permutations()
// 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]], ...]`
@ -1137,7 +1137,7 @@ function enumerate(l,idx=undef) =
// p = pair(list, <wrap>);
// for (p = pair(list, <wrap>)) ... // On each iteration, p contains a list of two adjacent items.
// Topics: List Handling, Iteration
// See Also: idx(), enumerate(), triplet(), permute()
// See Also: idx(), enumerate(), triplet(), combinations(), permutations()
// Description:
// Takes a list, and returns a list of adjacent pairs from it, optionally wrapping back to the front.
// Arguments:
@ -1167,7 +1167,7 @@ function pair(list, wrap=false) =
// list = triplet(list, <wrap>);
// for (t = triplet(list, <wrap>)) ...
// Topics: List Handling, Iteration
// See Also: idx(), enumerate(), pair(), permute()
// See Also: idx(), enumerate(), pair(), combinations(), permutations()
// Description:
// Takes a list, and returns a list of adjacent triplets from it, optionally wrapping back to the front.
// Example:
@ -1191,12 +1191,12 @@ function triplet(list, wrap=false) =
: [for (i=[0:1:ll-3]) [ list[i], list[i+1], list[i+2] ]];
// Function: permute()
// Function: combinations()
// Usage:
// list = permute(l, <n>);
// for (p = permute(l, <n>)) ...
// list = combinations(l, <n>);
// for (p = combinations(l, <n>)) ...
// Topics: List Handling, Iteration
// See Also: idx(), enumerate(), pair(), triplet()
// See Also: idx(), enumerate(), pair(), triplet(), permutations()
// 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]]`.
@ -1205,16 +1205,95 @@ function triplet(list, wrap=false) =
// 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]]
// pairs = combinations([3,4,5,6]); // Returns: [[3,4],[3,5],[3,6],[4,5],[4,6],[5,6]]
// triplets = combinations([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) =
// for (p=combinations(regular_ngon(n=7,d=100))) stroke(p);
function combinations(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)];
: [for (i=[_s:1:len(l)-n], p=combinations(l,n=n-1,_s=i+1)) concat([l[i]], p)];
// Function: permutations()
// Usage:
// list = permutations(l, <n>);
// for (p = permutations(l, <n>)) ...
// Topics: List Handling, Iteration
// See Also: idx(), enumerate(), pair(), triplet(), combinations()
// 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 = permutations([3,4,5,6]); // Returns: [[3,4],[3,5],[3,6],[4,5],[4,6],[5,6]]
// triplets = permutations([3,4,5,6],n=3); // Returns: [[3,4,5],[3,4,6],[3,5,6],[4,5,6]]
// Example(2D):
// for (p=permutations(regular_ngon(n=7,d=100))) stroke(p);
function permutations(l,n=2) =
assert(is_list(l), "Invalid list." )
assert( is_finite(n) && n>=1 && n<=len(l), "Invalid number `n`." )
n==1
? [for (i=[0:1:len(l)-1]) [l[i]]]
: [for (i=idx(l), p=permutations([for (j=idx(l)) if (i!=j) l[j]], n=n-1)) concat([l[i]], p)];
// Function: zip()
// Usage:
// pairs = zip(a,b);
// triples = zip(a,b,c);
// quads = zip([LIST1,LIST2,LIST3,LIST4]);
// Description:
// Zips together two or more lists into a single list. For example, if you have two
// lists [3,4,5], and [8,7,6], and zip them together, you get [[3,8],[4,7],[5,6]].
// The list returned will be as long as the shortest list passed to zip().
// Arguments:
// a = The first list, or a list of lists if b and c are not given.
// b = The second list, if given.
// c = The third list, if given.
// Example:
// a = [9,8,7,6]; b = [1,2,3];
// for (p=zip(a,b)) echo(p);
// // ECHO: [9,1]
// // ECHO: [8,2]
// // ECHO: [7,3]
function zip(a,b,c) =
b!=undef? zip([a,b,if (c!=undef) c]) :
let(n = list_shortest(a))
[for (i=[0:1:n-1]) [for (x=a) x[i]]];
// Function: zip_long()
// Usage:
// pairs = zip_long(a,b);
// triples = zip_long(a,b,c);
// quads = zip_long([LIST1,LIST2,LIST3,LIST4]);
// Description:
// Zips together two or more lists into a single list. For example, if you have two
// lists [3,4,5], and [8,7,6], and zip them together, you get [[3,8],[4,7],[5,6]].
// The list returned will be as long as the longest list passed to zip_long(), with
// shorter lists padded by the value in `fill`.
// Arguments:
// a = The first list, or a list of lists if b and c are not given.
// b = The second list, if given.
// c = The third list, if given.
// fill = The value to pad shorter lists with. Default: undef
// Example:
// a = [9,8,7,6]; b = [1,2,3];
// for (p=zip_long(a,b,fill=88)) echo(p);
// // ECHO: [9,1]
// // ECHO: [8,2]
// // ECHO: [7,3]
// // ECHO: [6,88]]
function zip_long(a,b,c,fill) =
b!=undef? zip_long([a,b,if (c!=undef) c],fill=fill) :
let(n = list_longest(a))
[for (i=[0:1:n-1]) [for (x=a) i<len(x)? x[i] : fill]];

8
tests/test_arrays.scad
View file

@ -468,11 +468,11 @@ module test_triplet() {
test_triplet();
module test_permute() {
assert(permute([3,4,5,6]) == [[3,4],[3,5],[3,6],[4,5],[4,6],[5,6]]);
assert(permute([3,4,5,6],n=3) == [[3,4,5],[3,4,6],[3,5,6],[4,5,6]]);
module test_combinations() {
assert(combinations([3,4,5,6]) == [[3,4],[3,5],[3,6],[4,5],[4,6],[5,6]]);
assert(combinations([3,4,5,6],n=3) == [[3,4,5],[3,4,6],[3,5,6],[4,5,6]]);
}
test_permute();
test_combinations();
module test_repeat_entries() {