How to get only one item of the a permutation from a list of strings

Question

I want to keep only one permutation among a set of strings and count the occurence of each permutation.

To make things more clear, I want to transform (for instance)

ab
acf
ba
cfa
acf

into

2 ab
3 acf

where 2 and 3 are the number of permutations of {a,b} and {a,c,f} respectively.

How would you do it in bash in the straightest possible way?

Is there any chance that any characters will be repeated within a single string? e.g. `abbc` — Arronical, Dec 06 '16 at 12:56
convert each string to a set of chars, or a sorted list of chars, and save that. In Python you could use itertools.permutations() to get all possible permutations (or number thereof). — boardrider, Dec 06 '16 at 19:44

choroba · Accepted Answer · 2016-12-06T13:27:38.530

Perl to the rescue!

perl -lne '$h{ join "", sort split // }++ }{ print "$h{$_} $_" for keys %h' < input_file

-n reads the input line by line
-l removes newlines from input, adds newlines to output
split // splits the string into characters
sort sorts them (hence uniqueness)
join "" creates back a single string from the list of characters
%h is a hash table, keys are the strings of sorted characters, values are numbers of occurrences: increased (++) on each encounter
}{ "Eskimo greeting" - separates the code to run after the input is exhausted

1 Answers1