1 USING: help.markup help.syntax math math.combinatorics
2 math.combinatorics.private math.order sequences ;
6 { $values { "n" "a non-negative integer" } { "n!" integer } }
7 { $description "Outputs the product of all positive integers less than or equal to " { $snippet "n" } "." }
9 { $example "USING: math.combinatorics prettyprint ;"
10 "4 factorial ." "24" }
14 { $values { "n" "a non-negative integer" } { "k" "a non-negative integer" } { "nPk" integer } }
15 { $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" } "." }
17 { $example "USING: math.combinatorics prettyprint ;"
22 { $values { "n" "a non-negative integer" } { "k" "a non-negative integer" } { "nCk" integer } }
23 { $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\"." }
25 { $example "USING: math.combinatorics prettyprint ;"
30 { $values { "n" "a non-negative integer" } { "seq" sequence } { "seq'" sequence } }
31 { $description "Outputs the " { $snippet "nth" } " lexicographical permutation of " { $snippet "seq" } "." }
32 { $notes "Permutations are 0-based and a bounds error will be thrown if " { $snippet "n" } " is larger than " { $snippet "seq length factorial 1 -" } "." }
34 { $example "USING: math.combinatorics prettyprint ;"
35 "1 { 0 1 2 } permutation ." "{ 0 2 1 }" }
36 { $example "USING: math.combinatorics prettyprint ;"
37 "5 { \"apple\" \"banana\" \"orange\" } permutation ." "{ \"orange\" \"banana\" \"apple\" }" }
41 { $values { "seq" sequence } { "permutations" sequence } }
42 { $description "An efficient sequence containing the lexicographical permutations of " { $snippet "seq" } "." } ;
44 HELP: <k-permutations>
45 { $values { "seq" sequence } { "k" integer } { "permutations" sequence } }
46 { $description "An efficient sequence containing the " { $snippet "k" } " lexicographical permutations of " { $snippet "seq" } "." } ;
48 HELP: all-permutations
49 { $values { "seq" sequence } { "seq'" sequence } }
50 { $description "Outputs a sequence containing all permutations of " { $snippet "seq" } " in lexicographical order." }
52 { $example "USING: math.combinatorics prettyprint ;"
53 "{ 0 1 2 } all-permutations ." "{ { 0 1 2 } { 0 2 1 } { 1 0 2 } { 1 2 0 } { 2 0 1 } { 2 1 0 } }" }
56 HELP: each-permutation
57 { $values { "seq" sequence } { "quot" { $quotation ( ... elt -- ... ) } } }
58 { $description "Applies the quotation to each permutation of " { $snippet "seq" } " in order." } ;
60 HELP: inverse-permutation
61 { $values { "seq" sequence } { "permutation" sequence } }
62 { $description "Outputs a sequence of indices representing the lexicographical permutation of " { $snippet "seq" } "." }
63 { $notes "All items in " { $snippet "seq" } " must be comparable by " { $link <=> } "." }
65 { $example "USING: math.combinatorics prettyprint ;"
66 "\"dcba\" inverse-permutation ." "{ 3 2 1 0 }" }
67 { $example "USING: math.combinatorics prettyprint ;"
68 "{ 12 56 34 78 } inverse-permutation ." "{ 0 2 1 3 }" }
72 { $values { "m" "a non-negative integer" } { "seq" sequence } { "k" "a non-negative integer" } { "seq'" sequence } }
73 { $description "Outputs the " { $snippet "mth" } " lexicographical combination of " { $snippet "seq" } " choosing " { $snippet "k" } " elements." }
74 { $notes "Combinations are 0-based and a bounds error will be thrown if " { $snippet "m" } " is larger than " { $snippet "seq length k nCk" } "." }
76 { $example "USING: math.combinatorics sequences prettyprint ;"
77 "6 7 <iota> 4 combination ." "{ 0 1 3 6 }" }
78 { $example "USING: math.combinatorics prettyprint ;"
79 "0 { \"a\" \"b\" \"c\" \"d\" } 2 combination ." "{ \"a\" \"b\" }" }
83 { $values { "seq" sequence } { "k" "a non-negative integer" } { "combinations" sequence } }
84 { $description "An efficient sequence containing the combinations of " { $snippet "seq" } " choosing " { $snippet "k" } " elements." } ;
86 HELP: all-combinations
87 { $values { "seq" sequence } { "k" "a non-negative integer" } { "seq'" sequence } }
88 { $description "Outputs a sequence containing all combinations of " { $snippet "seq" } " choosing " { $snippet "k" } " elements, in lexicographical order." }
90 { $example "USING: math.combinatorics prettyprint ;"
91 "{ \"a\" \"b\" \"c\" \"d\" } 2 all-combinations ."
101 HELP: each-combination
102 { $values { "seq" sequence } { "k" "a non-negative integer" } { "quot" { $quotation ( ... elt -- ... ) } } }
103 { $description "Applies the quotation to each combination of " { $snippet "seq" } " choosing " { $snippet "k" } " elements, in order." } ;
106 { $values { "n" integer } { "factoradic" sequence } }
107 { $description "Converts a positive integer " { $snippet "n" } " to factoradic form. The factoradic of an integer is its representation based on a mixed radix numerical system that corresponds to the values of " { $snippet "n" } " factorial." }
108 { $examples { $example "USING: math.combinatorics.private prettyprint ;" "859 factoradic ." "{ 1 1 0 3 0 1 0 }" } } ;
111 { $values { "factoradic" sequence } { "permutation" sequence } }
112 { $description "Converts an integer represented in factoradic form into its corresponding unique permutation (0-based)." }
113 { $notes "For clarification, the following two statements are equivalent:" { $code "10 factoradic >permutation" "{ 1 2 0 0 } >permutation" } }
114 { $examples { $example "USING: math.combinatorics.private prettyprint ;" "{ 0 0 0 0 } >permutation ." "{ 0 1 2 3 }" } } ;
116 HELP: next-permutation
117 { $values { "seq" sequence } }
118 { $description "Rearranges the elements in " { $snippet "seq" } " into the lexicographically next greater permutation of elements." }
119 { $notes "Performs an in-place modification of " { $snippet "seq" } "." }
120 { $examples { $example "USING: math.combinatorics prettyprint ;" "\"ABC\" next-permutation ." "\"ACB\"" } } ;
122 HELP: all-unique-permutations
123 { $values { "seq" sequence } { "seq'" sequence } }
124 { $description "Outputs a sequence containing all " { $strong "unique" } " permutations of " { $snippet "seq" } " in lexicographical order." }
126 { $example "USING: math.combinatorics prettyprint ;"
127 "{ 1 1 2 } all-unique-permutations ."
128 "{ { 1 1 2 } { 1 2 1 } { 2 1 1 } }" }
131 HELP: each-unique-permutation
132 { $values { "seq" sequence } { "quot" { $quotation ( ... elt -- ... ) } } }
133 { $description "Applies the quotation to each " { $strong "unique" } " permutation of " { $snippet "seq" } " in order." } ;
136 { $values { "seq" sequence } { "subsets" sequence } }
138 "Returns all the subsets of a sequence."
142 "USING: math.combinatorics prettyprint ;"
143 "{ 1 2 3 } all-subsets ."
144 "{ { } { 1 } { 2 } { 3 } { 1 2 } { 1 3 } { 2 3 } { 1 2 3 } }"
149 { $values { "seq" sequence } { "n" integer } { "seq'" sequence } }
151 "Returns all the ways to take n (possibly the same) items from the "
156 "USING: math.combinatorics prettyprint ;"
157 "{ 1 2 } 2 all-selections ."
158 "{ { 1 1 } { 1 2 } { 2 1 } { 2 2 } }"