1 ! Copyright (C) 2008 Doug Coleman, Michael Judge.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: assocs combinators generalizations kernel locals math
4 math.functions math.order math.vectors sequences
5 sequences.private sorting fry arrays grouping sets ;
9 [ sum ] [ length ] bi / ;
11 : geometric-mean ( seq -- x )
12 [ length ] [ product ] bi nth-root ;
14 : harmonic-mean ( seq -- x )
15 [ recip ] map-sum recip ;
17 : contraharmonic-mean ( seq -- x )
18 [ [ sq ] map-sum ] [ sum ] bi / ;
22 :: ((kth-object)) ( seq k nth-quot exchange-quot quot: ( x y -- ? ) -- elt )
23 #! Wirth's method, Algorithm's + Data structues = Programs p. 84
24 #! The algorithm modifiers seq, so we clone it
25 k seq bounds-check 2drop
38 [ i seq nth-quot call x quot call ] [ i 1 + i! ] while
39 [ x j seq nth-quot call quot call ] [ j 1 - j! ] while
41 i j seq exchange-quot call
52 : (kth-object) ( seq k nth-quot exchange-quot quot: ( x y -- ? ) -- elt )
53 [ clone ] 4dip ((kth-object)) ; inline
55 : kth-object-unsafe ( seq k quot: ( x y -- ? ) -- elt )
56 [ [ nth-unsafe ] [ exchange-unsafe ] ] dip (kth-object) ; inline
58 : kth-objects-unsafe ( seq kths quot: ( x y -- ? ) -- elts )
60 '[ [ nth-unsafe ] [ exchange-unsafe ] _ ((kth-object)) ] with map ; inline
64 : kth-object ( seq k quot: ( x y -- ? ) -- elt )
65 [ [ nth ] [ exchange ] ] dip (kth-object) ; inline
67 : kth-objects ( seq kths quot: ( x y -- ? ) -- elts )
69 '[ [ nth ] [ exchange ] _ ((kth-object)) ] with map ; inline
71 : kth-smallests ( seq kths -- elts ) [ < ] kth-objects-unsafe ;
73 : kth-smallest ( seq k -- elt ) [ < ] kth-object-unsafe ;
75 : kth-largests ( seq kths -- elts ) [ > ] kth-objects-unsafe ;
77 : kth-largest ( seq k -- elt ) [ > ] kth-object-unsafe ;
79 : count-relative ( seq k -- lt eq gt )
82 { +lt+ [ [ 1 + ] 2dip ] }
84 { +eq+ [ [ 1 + ] dip ] }
88 : minmax-relative ( seq k -- lt eq gt lt-max gt-min )
89 [ 0 0 0 -1/0. 1/0. ] 2dip '[
91 { +lt+ [ [ 1 + ] 5 ndip '[ _ max ] dip ] }
92 { +gt+ [ [ 1 + ] 3dip min ] }
93 { +eq+ [ [ 1 + ] 4dip drop ] }
97 : lower-median-index ( seq -- n )
99 [ length odd? [ 1 - ] unless ] bi ;
101 : lower-median ( seq -- elt )
102 [ ] [ lower-median-index ] bi kth-smallest ;
104 : upper-median ( seq -- elt )
105 dup midpoint@ kth-smallest ;
107 : medians ( seq -- lower upper )
109 [ [ lower-median-index ] [ midpoint@ ] bi 2array ]
110 bi kth-smallests first2 ;
112 : median ( seq -- x )
114 [ lower-median ] [ medians + 2 / ] if ;
116 ! quantile can be any n-tile. quartile is n = 4, percentile is n = 100
117 ! a,b,c,d parameters, N - number of samples, q is quantile (1/2 for median, 1/4 for 1st quartile)
118 ! http://mathworld.wolfram.com/Quantile.html
120 ! could subtract 1 from a
122 : quantile-x ( a b N q -- x )
123 [ + ] dip * + 1 - ; inline
127 >fraction [ /mod nip ] keep / ; inline
129 :: quantile-indices ( seq qs a b c d -- seq )
130 qs [ [ a b seq length ] dip quantile-x ] map ;
132 :: qabcd ( y-floor y-ceiling x c d -- qabcd )
133 y-floor y-ceiling y-floor - c d x frac * + * + ;
135 :: quantile-abcd ( seq qs a b c d -- quantile )
136 seq qs a b c d quantile-indices :> indices
137 indices [ [ floor ] [ ceiling ] bi 2array ] map
138 concat :> index-pairs
140 seq index-pairs kth-smallests
141 2 group indices [ [ first2 ] dip c d qabcd ] 2map ;
143 : quantile1 ( seq qs -- seq' )
144 0 0 1 0 quantile-abcd ;
146 : quantile3 ( seq qs -- seq' )
147 1/2 0 0 0 quantile-abcd ;
149 : quantile4 ( seq qs -- seq' )
150 0 0 0 1 quantile-abcd ;
152 : quantile5 ( seq qs -- seq' )
153 1/2 0 0 1 quantile-abcd ;
155 : quantile6 ( seq qs -- seq' )
156 0 1 0 1 quantile-abcd ;
158 : quantile7 ( seq qs -- seq' )
159 1 -1 0 1 quantile-abcd ;
161 : quantile8 ( seq qs -- seq' )
162 1/3 1/3 0 1 quantile-abcd ;
164 : quantile9 ( seq qs -- seq' )
165 3/8 1/4 0 1 quantile-abcd ;
167 : quartile ( seq -- seq' )
168 { 1/4 1/2 3/4 } quantile5 ;
172 : (sequence>assoc) ( seq map-quot: ( x -- ..y ) insert-quot: ( ..y assoc -- ) assoc -- assoc )
173 [ swap curry compose each ] keep ; inline
177 : sequence>assoc! ( assoc seq map-quot: ( x -- ..y ) insert-quot: ( ..y assoc -- ) -- assoc )
178 4 nrot (sequence>assoc) ; inline
180 : sequence>assoc ( seq map-quot: ( x -- ..y ) insert-quot: ( ..y assoc -- ) exemplar -- assoc )
181 clone (sequence>assoc) ; inline
183 : sequence>hashtable ( seq map-quot: ( x -- ..y ) insert-quot: ( ..y assoc -- ) -- hashtable )
184 H{ } sequence>assoc ; inline
186 : histogram! ( hashtable seq -- hashtable )
187 [ ] [ inc-at ] sequence>assoc! ;
189 : histogram-by ( seq quot: ( x -- bin ) -- hashtable )
190 [ inc-at ] sequence>hashtable ; inline
192 : histogram ( seq -- hashtable )
195 : sorted-histogram ( seq -- alist )
196 histogram sort-values ;
198 : collect-pairs ( seq quot: ( x -- v k ) -- hashtable )
199 [ push-at ] sequence>hashtable ; inline
201 : collect-by ( seq quot: ( x -- x' ) -- hashtable )
202 [ dup ] prepose collect-pairs ; inline
206 [ ] [ [ [ second ] bi@ > ] most ] map-reduce first ;
208 ERROR: empty-sequence ;
210 : minmax ( seq -- min max )
214 [ first dup ] keep [ [ min ] [ max ] bi-curry bi* ] each
220 : sample-var ( seq -- x )
225 [ [ mean ] keep [ - sq ] with map-sum ]
229 : full-var ( seq -- x )
233 [ [ mean ] keep [ - sq ] with map-sum ]
237 ALIAS: var sample-var
239 : sample-std ( seq -- x ) sample-var sqrt ;
241 : full-std ( seq -- x ) full-var sqrt ;
243 ALIAS: std sample-std
245 : mean-dev ( seq -- x ) dup mean v-n vabs mean ;
247 : median-dev ( seq -- x ) dup median v-n vabs mean ;
249 : sample-ste ( seq -- x ) [ sample-std ] [ length ] bi sqrt / ;
251 : full-ste ( seq -- x ) [ full-std ] [ length ] bi sqrt / ;
253 ALIAS: ste sample-ste
255 : ((r)) ( mean(x) mean(y) {x} {y} -- (r) )
256 ! finds sigma((xi-mean(x))(yi-mean(y))
257 0 [ [ [ pick ] dip swap - ] bi@ * + ] 2reduce 2nip ;
259 : (r) ( mean(x) mean(y) {x} {y} sx sy -- r )
260 * recip [ [ ((r)) ] keep length 1 - / ] dip * ;
262 : [r] ( {{x,y}...} -- mean(x) mean(y) {x} {y} sx sy )
263 first2 [ [ [ mean ] bi@ ] 2keep ] 2keep [ std ] bi@ ;
265 : r ( {{x,y}...} -- r )
268 : r^2 ( {{x,y}...} -- r )
271 : least-squares ( {{x,y}...} -- alpha beta )
272 [r] { [ 2dup ] [ ] [ ] [ ] [ ] } spread
273 ! stack is mean(x) mean(y) mean(x) mean(y) {x} {y} sx sy
274 [ (r) ] 2keep ! stack is mean(x) mean(y) r sx sy
275 swap / * ! stack is mean(x) mean(y) beta
278 : cov ( {x} {y} -- cov )
279 [ dup mean v-n ] bi@ v* mean ;
281 : sample-corr ( {x} {y} -- corr )
282 [ cov ] [ [ sample-var ] bi@ * sqrt ] 2bi / ;
284 : full-corr ( {x} {y} -- corr )
285 [ cov ] [ [ full-var ] bi@ * sqrt ] 2bi / ;
287 ALIAS: corr sample-corr
289 : cum-sum ( seq -- seq' )
290 0 swap [ + dup ] map nip ;
292 : cum-product ( seq -- seq' )
293 1 swap [ * dup ] map nip ;
295 : cum-min ( seq -- seq' )
296 [ ?first ] keep [ min dup ] map nip ;
298 : cum-max ( seq -- seq' )
299 [ ?first ] keep [ max dup ] map nip ;
301 : entropy ( seq -- n )
302 dup members [ [ = ] curry count ] with map
303 dup sum v/n dup [ log ] map v* sum neg ;
305 : binary-entropy ( p -- h )
306 [ dup log * ] [ 1 swap - dup log * ] bi + neg 2 log / ;
308 : standardize ( u -- v )
309 [ dup mean v-n ] [ std ] bi v/n ;
311 : differences ( u -- v )
312 [ 1 tail-slice ] keep [ - ] 2map ;
315 dup minmax over - [ v-n ] [ v/n ] bi* ;