[R] Modifying a particular column in a tab-delimited file

[Sashi Challa]

Hi Jim,

That is what I ended up doing. Each of my 1000 files has ~1 million rows, and 19 columns and it was taking 85 secs for every file to be just read into R. 
All I needed to do was replace one column with a particular vector values. So wanted to know if there was a way to do it without reading all the columns.
Thanks for your time,
Sashi

-----Original Message-----
From: jim holtman [mailto:jholtman at gmail.com] 
Sent: Wednesday, March 23, 2011 11:50 AM
To: Sashi Challa
Cc: r-help at r-project.org
Subject: Re: [R] Modifying a particular column in a tab-delimited file

Read the whole file in, modify the column and then write the file back out.

On Wed, Mar 23, 2011 at 12:03 PM, Sashi Challa <challa at ohsu.edu> wrote:
> Hello R users,
>
> Good day!!
>
> I was wondering if there is a way in R to read in a particular column from a tab-delimited file, edit it and write it back into the file with all other columns intact. When I say edit I mean just replacing all the values in that column.
> I know to read a particular column from a file using colClasses option in read.delim() function.
> Is there any such option to write out a column into an already existing file using write.table() function ??
>
> Thanks for your time
>
> -Sashi
>
>
>        [[alternative HTML version deleted]]
>
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-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?