From: Robert Klemme <shortcutter@...>
Date: 2006-10-21T01:20:14+09:00
Subject: Re: problem with reading file

On 20.10.2006 17:25, Li Chen wrote:
> Hi folks,
> 
> I read a file in the following format,extract the second column only, 
> and push them into an array. My problem is that Ruby reads them as 
> strings(based on array.inspect) but not as numbers so it is impossible 
> for me to do the calculation. Any comments?
> 
> Thanks,
> 
> Li
> 
> ###filen name: array.text
> 
> 
> A	1	B
> A	2	B
> A	3	B
> A	4	B
> A	5	B
> A	6	B
> 
> ..
> 
> ###script
> 
> equire 'enumerator'
> 
> array=Array.new
> 
> File.open('array.text').each{|line|  array<<line.split(/\t/)[1]}
> 
> #puts array.inspect
> array.each_slice(3){|slice|
>                    average=(slice[0]+slice[1]+slice[2])/(3.0)
>                    puts average
>                 }
> 
> ###output from screen
> 
> C:/Ruby/self/file6.rb:8: undefined method `/' for "123":String 
> (NoMethodError)
>         from 
> c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in 
> `each_slice'
>         from C:/Ruby/self/file6.rb:7:in `each'
>         from C:/Ruby/self/file6.rb:7:in `each_slice'
>         from C:/Ruby/self/file6.rb:7

This can be done by an awk style 1liner :-)

18:12:44 [Temp]: cat data
A       1       B
A       2       B
A       3       B
A       4       B
A       5       B
A       6       B
18:13:18 [Temp]: ruby -aF\\t -n -r enumerator -e 'BEGIN{$a=[]}; 
$a<<$F[1].to_i; END{ $a.each_slice(3){|sl| p 
sl.inject(0){|a,b|a+b}/3.0}}' data
2.0
5.0
18:13:34 [Temp]:

Kind regards

	robert