Programifications

A mashup of technical quirks

Enumberable#group_by

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So I have another boy on the way and I was trying to think up of names so I created a ruby script to pick a random name out of a file beginning with a letter that you provide as an argument. So you’d call the script like this:

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ruby boy_name.rb s
=> Sylen

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# using ruby 1.8.7

if ARGV.empty?
  puts "USAGE: ruby boy_name.rb <letter>"
  exit
end

file = File.open("boy_names.txt")
names = file.lines.to_a.group_by{|name| name[0,1]}
selected_names = names[ARGV[0].capitalize]
puts selected_names[rand(selected_names.size)]

What’s cool about it is this line

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names = file.lines.to_a.group_by{|name| name[0,1]}

Enumberable#group_by will group elements in an array by the result of the block passed in. In this case, we’re grouping by the first letter.

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%w{apple banana cucumber}.group_by{|fruit| fruit[0,1]}
=> #<OrderedHash {"a"=>["apple"], "b"=>["banana"], "c"=>["cucumber"]}>

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