CODEWITHSUNDEEP
rubyarrays
OscarRyz
OscarRyz

Reputation: 199225

Collect all not in using Ruby

I have this small snipped of code.

I don't know ruby and I think this is a great opportunity to apply it.

I want to print all the lines in file e which are not in file c. Each line is a number.

This is what I've got:

 e = File.new('e').readlines
 c = File.new('c').readlines

 x = e.collect do |item|
   c.include?( item ) ? "" : item
 end

 p x.sort

The problem is that both file may have empty spaces and for that reason the same number may not be considered as such. ( eg. "1234 " is different from " 1234 " )

What do I need in my code to fix it? I've tried c.include?(item.strip) .. .but doesn't seems to work.

Upvotes: 2

Views: 279

Answers (3)

klochner
klochner

Reputation: 8125

Two things:

  • you can use the minus operator for sets
  • why not convert to integers if each line is an integer?

  File.readlines("e").map(&:to_i) - File.readlines("c").map(&:to_i)

Upvotes: 3

Nate Kohl
Nate Kohl

Reputation: 35914

Perhaps doing the strip when you do the readlines would help, i.e.

e = File.readlines('e').map{|x| x.strip}
c = File.readlines('c').map{|x| x.strip}

Then you could use collect as you did, or perhaps select if you don't want the empty strings:

x = e.select{|i| !c.include?(i)}

Edit: or as Benno suggests, use

x = e-c

Upvotes: 3

bobDevil
bobDevil

Reputation: 29468

You can convert the items to actual numbers. Also, you should be closing those files after reading from them. File.new opens but does not close. You can open it in a block to automatically close it. Try:

e = nil
c = nil
File.open('e'){|file|
    e = file.readlines
    e.map!{|x| x.to_i}
}
File.open('c'){|file|
    c = file.readlines
    c.map!{|x| x.to_i}
}

To create the arrays of numbers.

Upvotes: 1

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