From: Robert Klemme <bob.news@...>
Date: 2003-04-24T17:47:10+09:00
Subject: Re: parsing large file into matrix


"Joel VanderWerf" <vjoel@PATH.Berkeley.EDU> schrieb im Newsbeitrag
news:3EA77CED.8010201@path.berkeley.edu...
> Qubert wrote:
>
> > Is there a Ruby-way of creating an m by n array from the beginning?
> > I know the following doesn't work but something like it code would be
nice:
> > x = File.open("file.txt").readlines.split('\t')
>
> How about this?
>
>   x = File.open("file.txt").readlines.
>         map {|line| line.chomp.split("\t").
>                       map {|s|s.to_f}}

I don't think this closes the file properly. And, another disadvantage, it
keeps the whole file in memory.  How about

# read
matrix=[]
File.open("file.txt").each{|line|
  matrix << ( line.chomp.split("\t").map {|s|s.to_f} )
  # alternative use split( /\s+/ ) to use all white space as separator
}

# write again
matrix.each{|x| puts x.join "\t"}

    robert