I have a large csv. I want to delete the first line of the file. How is this done? I don't want to copy every line into an array and rewrite them for the previous index and delete the first. There must be a better way. (maybe with fastercsv? how?)
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Not a Rails specific question.Yoann Le Touche– Yoann Le Touche2012-02-16 12:03:01 +00:00Commented Feb 16, 2012 at 12:03
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4 Answers
If you don't mind shelling out to a command line, it is particularly efficient:
system("tail -n +2 #{input} > #{output}")
Comments
Something like :
source=File::open("source","r")
dest=File::open("dest","w")
source.each_line do |line|
next if f.lineno == 1
dest.write(line)
end
source.close
dest.close
3 Comments
David Unric
Wrong, whole source file is read into memory questioner would like to avoid.
Yoann Le Touche
My bad, I read the question too quickly. Here's a modified version reading the file line by line
Michael Kohl
You are not closing the file handles. Either close them explicitly or use the block form of
File.open.Copy the file to another file, omitting the line(s) you want deleted. You don't have to load the file into an array, just read and write line by line within the same loop.
answered Feb 16, 2012 at 11:37
Mladen Jablanović
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Comments
You mean like this?
source_path = 'liner.txt'
open source_path do |input|
input.gets
open "#{source_path}.header_removed", 'w' do |output|
input.each do |line|
output << line
end
end
end
But, this code require simple format for CSV
