Hi,
very often while doing maintenance work on a datawarehouse using CSV
files as input, I need to keep only the first line (headers) and any
line matching a given regexp, in order to save some time.
Here's a little helper do to this:
def keep_headers_and_matching_lines(filename,regexp)
tempfilename = filename + ".tmp"
FileUtils.mv(filename,tempfilename)
File.open(tempfilename) do |input|
File.open(filename,'w') do |output|
input.each_with_index do |line,index|
output << line if (line =~ regexp || index == 0)
end
end
end
end
Typical use:
preprocess { keep_headers_and_matching_lines('mydata.csv',/customer/i) }
(sure that can be done also with a grep call - and that would be faster as well)
in case it's useful to someone else !
cheers,
Thibaut Barrère
--
[blog] http://evolvingworker.com - tools for a better day
[blog] http://blog.logeek.fr - about writing software
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