Extract lines with regular expressions

ruby-talk
1

I am a newb trying to take a list of data in a text file and print out a
new list of lines that contain certain characters...
I am not too worried about the actual regex - I can figure that out -
but I cannot seem to get it to implement correctly.

I found the following online (http://www.fepus.net/ruby1line.txt)

# print only lines that match a regular expression (emulates 'grep')
    $ ruby -pe 'next unless $_ =~ /regexp/' < file.txt

and it does exactly what I want, but...

how do I use this (or something similar, ie grep) in a .rb script?

I have tried this:
vl_stops.each do |vl_stops|
   puts "#{vl_stops}"
   search = Regexp.new("^\b(#{vl_stops}:)\w*")
   files.each do |file|
   f = File.open(directory+file)
      f.grep(search)
         puts #what goes here? line?
      end
      f.close
   end
puts
end
based on something I found here
(http://www.rousette.org.uk/blog/archives/2004/10/21/gtd-using-text-files/)

But I am not sure how to seal the deal, as it were...
Any thoughts would be appreciated.
Thanks!

···

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Posted via http://www.ruby-forum.com/.

2

files.each do |file|
    File.open(directory+file) do |f|
       puts f.grep(search)
    end

Or, for large files

    files.each do |file|
    File.open(directory+file) do |f|
       f.each do |line|
         puts line if search ~= line
       end
    end

Kind regards

  robert

···

On 21.04.2008 07:49, Michael Dore wrote:

I am a newb trying to take a list of data in a text file and print out a
new list of lines that contain certain characters...
I am not too worried about the actual regex - I can figure that out -
but I cannot seem to get it to implement correctly.

I found the following online (fepus.net)

# print only lines that match a regular expression (emulates 'grep')
    $ ruby -pe 'next unless $_ =~ /regexp/' < file.txt

and it does exactly what I want, but...

how do I use this (or something similar, ie grep) in a .rb script?

I have tried this:
vl_stops.each do |vl_stops|
   puts "#{vl_stops}"
   search = Regexp.new("^\b(#{vl_stops}:)\w*")
   files.each do |file|
   f = File.open(directory+file)
      f.grep(search)
         puts #what goes here? line?
      end
      f.close
   end
puts
end
based on something I found here
(http://www.rousette.org.uk/blog/archives/2004/10/21/gtd-using-text-files/\)

But I am not sure how to seal the deal, as it were...
Any thoughts would be appreciated.
Thanks!

3

Michael Dore wrote:

I have tried this:

vl_stops.each do |vl_stops|

First, you might try dreaming up more than one variable name.

Second, if you are searching for simple strings, like 'hello', you can
do this:

search_string = 'hello'

IO.foreach("data.txt") do |line|
  if line.include?(search_string)
    puts line
  end
end

···

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