How do I parse columns in a CSV File in Ruby and store it as an array?

Question

I have the following CSV file:

Date,Av,Sec,128,440,1024,Mixed,,rule,sn,version

6/30/2010,3.40,343,352.0,1245.8,3471.1,650.7,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 342,-0.26%,-0.91%,1.51%,-0.97%
6/24/2010,3.40,342,352.9,1257.2,3419.5,657.1,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 341,0.23%,0.50%,-1.34%,0.67%
6/17/2010,3.40,341,352.1,1251.0,3466.1,652.7,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 340,7.77%,5.32%,9.04%,1.71%
6/14/2010,3.40,340,326.7,1187.8,3178.7,641.7,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 339,-0.88%,-0.34%,-0.95%,0.05%
6/11/2010,3.40,339,329.6,1191.9,3209.2,641.4,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 338,0.58%,0.51%,-1.83%,0.99%
6/11/2010,3.40,338,327.7,1185.8,3269.1,635.1,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 335,-0.40%,-0.44%,1.46%,-1.96%
6/11/2010,3.40,335,329.0,1191.0,3221.9,647.8,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 333,-6.83%,-4.70%,-7.04%,-0.32%
6/11/2010,3.40,333,353.1,1249.8,3465.8,649.9,Mbps,on,s-2.8.6-38,4.9.1-229,,vs. 332,2.53%,2.02%,1.71%,2.14%

and I want to parse columns 4, 5, 6 and 7 and have four arrays, on which I can do operations like create a line graph against time, etc.

Martin Carpenter · Accepted Answer · 2010-07-13 13:56:24Z

4

You need the Ruby CSV module which ships with Ruby. Example:

require 'csv'
require 'pp'

file = File.open( 'bar.csv' )
CSV::Reader.create( file ).each do |row|
  pp row[4..7]
end

edited Jul 13, 2010 at 13:56

answered Jul 13, 2010 at 13:49

Martin Carpenter

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Salil · Accepted Answer · 2010-07-13 13:49:40Z

0

why reinvent the wheel!

Use plugin fastercsv or csv

answered Jul 13, 2010 at 13:49

Salil

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the Tin Man · Accepted Answer · 2012-04-06 19:41:53Z

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You are spoiled for choice in parsing CSVs with Ruby, as there are options included in the standard lib, as well as easy home-brewed methods or Open Source libs.

You can start with the examples on "How to parse CSV data with Ruby", and that should point you in the direction for digging deeper.

edited Apr 6, 2012 at 19:41

the Tin Man

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answered Jul 13, 2010 at 13:50

ewall

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Tilo · Accepted Answer · 2013-04-13 20:15:41Z

0

you can use the smarter_csv Ruby gem and use a :key_mapping to ignore unwanted input columns.

See:

https://github.com/tilo/smarter_csv

answered Apr 13, 2013 at 20:15

Tilo

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