Read data line by line

ruby-talk
1

could anybody please give me an example of how to read data from a text
file line by line so that manipulations can be made on each and
everyline and copy those to other file?

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

2

Harry

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On 4/7/07, Krishna Vutukuru <krishna.vutukuru@consultrcg.com> wrote:

could anybody please give me an example of how to read data from a text
file line by line so that manipulations can be made on each and
everyline and copy those to other file?

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

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Japanese Ruby List Subjects in English

3

File.open("output.txt", "w") do |output|
   File.foreach("input.txt") do |line|
     # change line here...
     output << line
   end
end

Hope that helps.

James Edward Gray II

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On Apr 6, 2007, at 11:51 PM, Krishna Vutukuru wrote:

could anybody please give me an example of how to read data from a text
file line by line so that manipulations can be made on each and
everyline and copy those to other file?

4

James Edward Gray II wrote:

···

On Apr 6, 2007, at 11:51 PM, Krishna Vutukuru wrote:

> could anybody please give me an example of how to read data from a
> text file line by line so that manipulations can be made on each
> and everyline and copy those to other file?

File.open("output.txt", "w") do |output| File.foreach("input.txt") do
>line> # change line here... output << line end end

Hope that helps.

James Edward Gray II

As well as something like this

lines=File.readlines("filename")
lines.collect!{|l| do something with l and give it back}
File.open("output","w"){|f| f<<lines.join("\n")}

Pedantic, I know :slight_smile:
V.-
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http://www.braveworld.net/riva

5

The problem with your solution is that it slurps all the data into memory at once. For large data sets, this may not be an option.

My solution only reads one line at a time and thus is a lot more memory friendly.

James Edward Gray II

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On Apr 9, 2007, at 6:55 AM, Vassilis Rizopoulos wrote:

James Edward Gray II wrote:

On Apr 6, 2007, at 11:51 PM, Krishna Vutukuru wrote:

> could anybody please give me an example of how to read data from a
> text file line by line so that manipulations can be made on each
> and everyline and copy those to other file?

File.open("output.txt", "w") do |output| File.foreach("input.txt") do
>line> # change line here... output << line end end

Hope that helps.

James Edward Gray II

As well as something like this

lines=File.readlines("filename")
lines.collect!{|l| do something with l and give it back}
File.open("output","w"){|f| f<<lines.join("\n")}

Pedantic, I know :slight_smile: