From: Rob Biedenharn <Rob@...>
Date: 2010-01-22T07:54:22+09:00
Subject: Re: an elegant way to modify all lines from file by using map()  function?

On Jan 21, 2010, at 5:40 PM, Benoit Daloze wrote:
> Hi,
>
> 2010/1/21 RobertGawron <mojwpisdao@gmail.com>
>
>> Hi all,
>>
>> I'm new in ruby and I just have a question: in python when I want to
>> read all lines from file, do something with all of them and then use
>> them in my program I use map function + lambda function, sth like
>> that:
>>
>> print map(lambda u: u.upper(), open("foo", "r").readlines())
>>
>> but in your language I didn't find the way to create in one step  
>> array
>> of all lines from file, that could be used by map(). If I really want
>> to use map in this situation I have to use secondary array (called
>> arr) like in this snippet?
>>
>> arr = Array.new
>> File.open('foo').each_line{ |l| arr.push l }
>> p arr.collect{ |l| l.upcase }
>>
>> Please post a code-snippet, it's quite interesting to me :)
>>
>>
> Waow awesome how the order is in Python...
>
> Let's take the natural order, welcome to Ruby !
>
> puts File.read('foo').lines.map { |line| line.upcase }
> That's in ruby 1.9
> Notice lines is an Enumerator, that can be converted to an Array if  
> needed
> by #to_a
>
> You got also IO.readlines


Don't stop there! Take advantage of the Symbol#to_proc behavior:

puts File.read('foo').lines.map(&:upcase)

;-)

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com