1 USING: help.markup help.syntax sequences strings ;
4 ARTICLE: "grouping" "Groups and clumps"
5 "Splitting a sequence into disjoint, fixed-length subsequences:"
7 "A virtual sequence for splitting a sequence into disjoint, fixed-length subsequences:"
9 { $subsection <groups> }
10 { $subsection <sliced-groups> }
11 "Splitting a sequence into overlapping, fixed-length subsequences:"
13 "A virtual sequence for splitting a sequence into overlapping, fixed-length subsequences:"
14 { $subsection clumps }
15 { $subsection <clumps> }
16 { $subsection <sliced-clumps> }
17 "The difference can be summarized as the following:"
19 { "With groups, the subsequences form the original sequence when concatenated:"
22 "{ 1 2 3 4 } dup" "2 <groups> concat sequence= ." "t"
25 { "With clumps, collecting the first element of each subsequence but the last one, together with the last subseqence, yields the original sequence:"
28 "{ 1 2 3 4 } dup" "2 <clumps> unclip-last [ [ first ] map ] dip append sequence= ." "t"
32 "A combinator built using clumps:"
33 { $subsection monotonic? }
34 "Testing how elements are related:"
35 { $subsection all-eq? }
36 { $subsection all-equal? } ;
41 { $class-description "Instances are virtual sequences whose elements are disjoint fixed-length subsequences of an underlying sequence. Groups are mutable and resizable if the underlying sequence is mutable and resizable, respectively."
43 "New groups are created by calling " { $link <groups> } " and " { $link <sliced-groups> } "." } ;
46 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "array" "a sequence of sequences" } }
47 { $description "Splits the sequence into disjoint groups of " { $snippet "n" } " elements and collects the groups into a new array." }
48 { $notes "If the sequence length is not a multiple of " { $snippet "n" } ", the final subsequence in the list will be shorter than " { $snippet "n" } " elements." }
50 { $example "USING: grouping prettyprint ;" "{ 3 1 3 3 7 } 2 group ." "{ { 3 1 } { 3 3 } { 7 } }" }
54 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "groups" groups } }
55 { $description "Outputs a virtual sequence whose elements are disjoint subsequences of " { $snippet "n" } " elements from the underlying sequence." }
58 "USING: arrays kernel prettyprint sequences grouping ;"
59 "9 >array 3 <groups> dup reverse-here concat >array ." "{ 6 7 8 3 4 5 0 1 2 }"
62 "USING: kernel prettyprint sequences grouping ;"
63 "{ 1 2 3 4 5 6 } 3 <groups> first ."
69 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "groups" groups } }
70 { $description "Outputs a virtual sequence whose elements are slices of disjoint subsequences of " { $snippet "n" } " elements from the underlying sequence." }
73 "USING: arrays kernel prettyprint sequences grouping ;"
74 "9 >array 3 <sliced-groups>"
75 "dup [ reverse-here ] each concat >array ."
76 "{ 2 1 0 5 4 3 8 7 6 }"
79 "USING: kernel prettyprint sequences grouping ;"
80 "{ 1 2 3 4 5 6 } 3 <sliced-groups> second ."
81 "T{ slice { from 3 } { to 6 } { seq { 1 2 3 4 5 6 } } }"
86 { $class-description "Instances are virtual sequences whose elements are overlapping fixed-length subsequences o an underlying sequence. Clumps are mutable and resizable if the underlying sequence is mutable and resizable, respectively."
88 "New clumps are created by calling " { $link <clumps> } " and " { $link <sliced-clumps> } "." } ;
91 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "array" "a sequence of sequences" } }
92 { $description "Splits the sequence into overlapping clumps of " { $snippet "n" } " elements and collects the clumps into a new array." }
93 { $errors "Throws an error if " { $snippet "n" } " is smaller than the length of the sequence." }
95 { $example "USING: grouping prettyprint ;" "{ 3 1 3 3 7 } 2 clump ." "{ { 3 1 } { 1 3 } { 3 3 } { 3 7 } }" }
99 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "clumps" clumps } }
100 { $description "Outputs a virtual sequence whose elements are overlapping subsequences of " { $snippet "n" } " elements from the underlying sequence." }
104 "USING: grouping sequences math prettyprint kernel ;"
106 "CONSTANT: share-price { 13/50 51/100 13/50 1/10 4/5 17/20 33/50 3/25 19/100 3/100 }"
108 "share-price 4 <clumps> [ [ sum ] [ length ] bi / ] map ."
109 "{ 113/400 167/400 201/400 241/400 243/400 91/200 1/4 }"
112 "USING: kernel sequences grouping prettyprint ;"
113 "{ 1 2 3 4 5 6 } 3 <clumps> second ."
118 HELP: <sliced-clumps>
119 { $values { "seq" "a sequence" } { "n" "a non-negative integer" } { "clumps" clumps } }
120 { $description "Outputs a virtual sequence whose elements are overlapping slices of " { $snippet "n" } " elements from the underlying sequence." }
123 "USING: kernel sequences grouping prettyprint ;"
124 "{ 1 2 3 4 5 6 } 3 <sliced-clumps> second ."
125 "T{ slice { from 1 } { to 4 } { seq { 1 2 3 4 5 6 } } }"
129 { clumps groups } related-words
131 { clump group } related-words
133 { <clumps> <groups> } related-words
135 { <sliced-clumps> <sliced-groups> } related-words
138 { $values { "seq" sequence } { "quot" { $quotation "( elt elt -- ? )" } } { "?" "a boolean" } }
139 { $description "Applies the relation to successive pairs of elements in the sequence, testing for a truth value. The relation should be a transitive relation, such as a total order or an equality relation." }
141 "Testing if a sequence is non-decreasing:"
142 { $example "USING: grouping math prettyprint ;" "{ 1 1 2 } [ <= ] monotonic? ." "t" }
143 "Testing if a sequence is decreasing:"
144 { $example "USING: grouping math prettyprint ;" "{ 9 8 6 7 } [ < ] monotonic? ." "f" }
148 { $values { "seq" sequence } { "?" "a boolean" } }
149 { $description "Tests if all elements in the sequence are equal. Yields true with an empty sequence." } ;
152 { $values { "seq" sequence } { "?" "a boolean" } }
153 { $description "Tests if all elements in the sequence are the same identical object. Yields true with an empty sequence." } ;
155 { monotonic? all-eq? all-equal? } related-words