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Anagrams in a word list in K (Kona)
/
/ Here we explain a K function that shows all words in a word list
/ that are anagrams.
/
/
/ The K function used was found here:
/ http://lambda-the-ultimate.org/node/1323
/ Define the function
anagram: {x g@&1<#:'g:={x@<x}'x}
/ Read the word list "word.list" and assign to the variable a
/ (The ";" means that nothing is printed.)
a: 0: "word.lst" ;
/ show all anagrams, i.e. partitions which contains
/ of 2 or more words
anagram a
/ a lot of output....
/
/ Let's see how it works with a smaller example.
/
/ define the word list
b: ("algorithm";"parse";"astrid";"sunday";"algorithm";"morning";"pears")
/ There are two anagram partitions:
anagram b
(("algorithm"
"algorithm")
("parse"
"pears"))
/
/ Here is how it works.
/
/ the anagram function again (for reference)
{x g@&1<#:'g:={x@<x}'x}
/ Sort each word, and assign to g
g:{x@<x}' b
("aghilmort"
"aeprs"
"adirst"
"adnsuy"
"aghilmort"
"gimnnor"
"aeprs")
/ group the sorted words into partitions (equivalence classes)
/ according to the its sorted version
/ = is the group function
/ Here we see that there are two partitions with 2 words
/ (0 4) and (1 6)
={x@<x}' b
(0 4
1 6
,2
,3
,5)
/ count (#) the number of (sorted) words in each partition
#:'g:={x@<x}'b
2 2 1 1 1
/ we just want those partitions with more than one word
/ (1 is boolean true)
1<#:'g:={x@<x}'b
1 1 0 0 0
/ get the index of these partitions
/ (i.e. the first two partitions)
&1<#:'g:={x@<x}'b
0 1
/ now get the words as index in the word list for these partitions
g@&1<#:'g:={x@<x}' b
(0 4
1 6)
/ and last, lookup these word in the original word list
b g@&1<#:'g:={x@<x}' b
(("algorithm"
"algorithm")
("parse"
"pears"))
/ Now we can make this a function by replacing the argument
/ "b" (the word list) with "x" (the first argument of
/ a function), and place { } around the expression to make
/ it a function.
{x g@&1<#:'g:={x@<x}'x}
A note about the speed.
-----------------------
I'm quite impressed by the speed of this in Kona.
* Kona is fast reading a file into memory:
a) Reading a word list with 173528 words (1.7M bytes) takes
about 30 milliseconds.
b) Reading a larger file of 1114610 (Swedish) words (12.6M bytes)
takes about 110ms.
* both reading and checking for anagrams and output the number
of partitions is also very fast.
a) Smallest word list: 0.46s
b) Larger word list: 2.99s
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