Add docs for combination words

basis/math/combinatorics/combinatorics-docs.factor

@@ -1,37 +1,93 @@
-USING: help.markup help.syntax kernel math math.order sequences ;
+USING: help.markup help.syntax kernel math math.order multiline sequences ;
 IN: math.combinatorics
 
 HELP: factorial
 { $values { "n" "a non-negative integer" } { "n!" integer } }
 { $description "Outputs the product of all positive integers less than or equal to " { $snippet "n" } "." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "4 factorial ." "24" } } ;
+{ $examples 
+    { $example "USING: math.combinatorics prettyprint ;"
+        "4 factorial ." "24" }
+} ;
 
 HELP: nPk
 { $values { "n" "a non-negative integer" } { "k" "a non-negative integer" } { "nPk" integer } }
 { $description "Outputs the total number of unique permutations of size " { $snippet "k" } " (order does matter) that can be taken from a set of size " { $snippet "n" } "." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "10 4 nPk ." "5040" } } ;
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "10 4 nPk ." "5040" }
+} ;
 
 HELP: nCk
 { $values { "n" "a non-negative integer" } { "k" "a non-negative integer" } { "nCk" integer } }
 { $description "Outputs the total number of unique combinations of size " { $snippet "k" } " (order does not matter) that can be taken from a set of size " { $snippet "n" } ". Commonly written as \"n choose k\"." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "10 4 nCk ." "210" } } ;
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "10 4 nCk ." "210" }
+} ;
 
 HELP: permutation
 { $values { "n" "a non-negative integer" } { "seq" sequence } { "seq" sequence } }
 { $description "Outputs the " { $snippet "nth" } " lexicographical permutation of " { $snippet "seq" } "." }
 { $notes "Permutations are 0-based and a bounds error will be thrown if " { $snippet "n" } " is larger than " { $snippet "seq length factorial 1-" } "." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "1 3 permutation ." "{ 0 2 1 }" } { $example "USING: math.combinatorics prettyprint ;" "5 { \"apple\" \"banana\" \"orange\" } permutation ." "{ \"orange\" \"banana\" \"apple\" }" } } ;
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "1 3 permutation ." "{ 0 2 1 }" }
+    { $example "USING: math.combinatorics prettyprint ;"
+        "5 { \"apple\" \"banana\" \"orange\" } permutation ." "{ \"orange\" \"banana\" \"apple\" }" }
+} ;
 
 HELP: all-permutations
 { $values { "seq" sequence } { "seq" sequence } }
 { $description "Outputs a sequence containing all permutations of " { $snippet "seq" } " in lexicographical order." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "3 all-permutations ." "{ { 0 1 2 } { 0 2 1 } { 1 0 2 } { 1 2 0 } { 2 0 1 } { 2 1 0 } }" } } ;
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "3 all-permutations ." "{ { 0 1 2 } { 0 2 1 } { 1 0 2 } { 1 2 0 } { 2 0 1 } { 2 1 0 } }" }
+} ;
+
+HELP: each-permutation
+{ $values { "seq" sequence } { "quot" { $quotation "( seq -- )" } } }
+{ $description "Applies the quotation to each permuation of " { $snippet "seq" } " in order." } ;
 
 HELP: inverse-permutation
 { $values { "seq" sequence } { "permutation" sequence } }
 { $description "Outputs a sequence of indices representing the lexicographical permutation of " { $snippet "seq" } "." }
 { $notes "All items in " { $snippet "seq" } " must be comparable by " { $link <=> } "." }
-{ $examples { $example "USING: math.combinatorics prettyprint ;" "\"dcba\" inverse-permutation ." "{ 3 2 1 0 }" } { $example "USING: math.combinatorics prettyprint ;" "{ 12 56 34 78 } inverse-permutation ." "{ 0 2 1 3 }" } } ;
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "\"dcba\" inverse-permutation ." "{ 3 2 1 0 }" }
+    { $example "USING: math.combinatorics prettyprint ;"
+        "{ 12 56 34 78 } inverse-permutation ." "{ 0 2 1 3 }" }
+} ;
+
+HELP: combination
+{ $values { "m" "a non-negative integer" } { "seq" sequence } { "k" "a non-negative integer" } { "seq" sequence } }
+{ $description "Outputs the " { $snippet "mth" } " lexicographical combination of " { $snippet "seq" } " choosing " { $snippet "k" } " elements." }
+{ $notes "Combinations are 0-based and a bounds error will be thrown if " { $snippet "m" } " is larger than " { $snippet "seq length k nCk" } "." }
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "6 7 iota 4 combination ." "{ 0 1 3 6 }" }
+    { $example "USING: math.combinatorics prettyprint ;"
+        "0 { \"a\" \"b\" \"c\" \"d\" } 2 combination ." "{ \"a\" \"b\" }" }
+} ;
+
+HELP: all-combinations
+{ $values { "seq" sequence } { "k" "a non-negative integer" } { "seq" sequence } }
+{ $description "Outputs a sequence containing all combinations of " { $snippet "seq" } " choosing " { $snippet "k" } " elements, in lexicographical order." }
+{ $examples
+    { $example "USING: math.combinatorics prettyprint ;"
+        "{ \"a\" \"b\" \"c\" \"d\" } 2 all-combinations ."
+<" {
+    { "a" "b" }
+    { "a" "c" }
+    { "a" "d" }
+    { "b" "c" }
+    { "b" "d" }
+    { "c" "d" }
+}"> } } ;
+
+HELP: each-combination
+{ $values { "seq" sequence } { "k" "a non-negative integer" } { "quot" { $quotation "( seq -- )" } } }
+{ $description "Applies the quotation to each combination of " { $snippet "seq" } " choosing " { $snippet "k" } " elements, in order." } ;
 
 
 IN: math.combinatorics.private