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sorting.extras: adding bisect-right and bisect-left.

db4
John Benediktsson 2013-09-05 21:07:50 -07:00
parent dba072e9f2
commit 13db93639f
2 changed files with 28 additions and 2 deletions
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8
extra/sorting/extras/extras-tests.factor
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@ -10,3 +10,11 @@ IN: sorting.extras
{ "green" "blue" "purple" } [ length ] map-sort { "green" "blue" "purple" } [ length ] map-sort
] unit-test ] unit-test
{ 1 { 1 2 3 4 } } [ 1 { 4 2 1 3 } [ dupd + ] map-sort ] unit-test { 1 { 1 2 3 4 } } [ 1 { 4 2 1 3 } [ dupd + ] map-sort ] unit-test
{ 0 } [ 0 { 1 } bisect-right ] unit-test
{ 1 } [ 1 { 1 } bisect-right ] unit-test
{ 1 } [ 2 { 1 } bisect-right ] unit-test
{ 0 } [ 0 { 1 } bisect-left ] unit-test
{ 0 } [ 1 { 1 } bisect-left ] unit-test
{ 1 } [ 2 { 1 } bisect-left ] unit-test

22
extra/sorting/extras/extras.factor
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@ -1,5 +1,5 @@
USING: arrays assocs kernel kernel.private sequences USING: arrays assocs kernel kernel.private locals math
sequences.private sorting ; math.order sequences sequences.private sorting ;
IN: sorting.extras IN: sorting.extras
: argsort ( seq quot: ( obj1 obj2 -- <=> ) -- sortedseq ) : argsort ( seq quot: ( obj1 obj2 -- <=> ) -- sortedseq )
@ -11,3 +11,21 @@ IN: sorting.extras
[ map ] curry keep zip [ map ] curry keep zip
[ { array } declare first-unsafe ] sort-with [ { array } declare first-unsafe ] sort-with
[ { array } declare second-unsafe ] map ; inline [ { array } declare second-unsafe ] map ; inline
:: bisect-left ( obj seq -- i )
0 seq length [ 2dup < ] [
2dup + 2/ dup seq nth-unsafe obj before?
[ swap [ nip 1 + ] dip ] [ nip ] if
] while drop ;
:: bisect-right ( obj seq -- i )
0 seq length [ 2dup < ] [
2dup + 2/ dup seq nth-unsafe obj after?
[ nip ] [ swap [ nip 1 + ] dip ] if
] while drop ;
: insort-left ( obj seq -- seq' )
[ bisect-left ] 2keep swapd insert-nth ;
: insort-right ( obj seq -- seq' )
[ bisect-right ] 2keep swapd insert-nth ;