string - Properly combining words in a file using Ruby

Question

I have a file full of words and I am trying to write a script that basically makes every combination of 2 words from that list to another list.

require 'tempfile'
require 'fileutils'

path = 'Lst.lst'
temp_file = Tempfile.new('lst2.lst')
begin
  File.open(path, 'r') do |file|
    file.readlines(file).each do |line|
         file.each_line do |baseline|
                temp_file.puts line.gsub("
", '') + baseline
        end
    end
 end
  temp_file.close
  FileUtils.mv(temp_file.path, 'lst2.lst')
ensure
  temp_file.close
  temp_file.unlink
end

The script runs but the outer loop only runs once. How can I fix this?

question from:https://stackoverflow.com/questions/65944972/properly-combining-words-in-a-file-using-ruby

Answer 1

Use Iterators Instead of Nested Loops

In general, explicit looping in Ruby is not idiomatic, although there are always exceptions. You'll often find it easier to perform what you want using an object's native iterators.

Given a file like word_list.txt with a small set of contents like this:

a
b
c
d
e
f
g

you can use Array#combination to make your pairwise combinations. For example, with Ruby 3.0.0:

words      = File.readlines('word_list.txt').map &:chomp
word_pairs = words.combination 2

File.open('new_list.txt', 'w') do |file|
  word_pairs.map { file.puts "#{_1}#{_2}" }
end 

You can then verify the results of your output in the shell:

$ cat new_list.txt 
a   b
a   c
a   d
a   e
a   f
a   g
b   c
b   d
b   e
b   f
b   g
c   d
c   e
c   f
c   g
d   e
d   f
d   g
e   f
e   g
f   g