R help - Jul 2008 - how do I read only specific columns using read.csv or other read function

Hi R people:

I have huge files with as many as 5000 columns. I'd really like to read 
only certain columns of those files. I know column names I want to read.

I looked at the documentation of read.csv . Although there is a 
col.names option, it allows users to specify the names of the columns, 
rather than to pick the columns of interest.

Any suggestions on how to pick the columns I want to read only, rather 
than the entire file, would be greatly appreciated.

Phil Smith
Duluth, GA

On Jul 2, 2008, at 6:53 AM, Philip James Smith wrote:
> Hi R people:
>
> I have huge files with as many as 5000 columns. I'd really like to  
> read only certain columns of those files. I know column names I  
> want to read.
>
> I looked at the documentation of read.csv . Although there is a  
> col.names option, it allows users to specify the names of the  
> columns, rather than to pick the columns of interest.
>
> Any suggestions on how to pick the columns I want to read only,  
> rather than the entire file, would be greatly appreciated.
>
Hello,

I think you want explicitly set the colClasses argument such that the  
columns you *don't* want are set to NULL and all others are set to  
appropriate classes.

Cheers,
Ben





> Phil Smith
> Duluth, GA
>
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Ben Tupper
PemaquidRiver at tidewater.net

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