R help - Mar 2011 - How to read only specified columns from a data file

R-help,

I'm trying to read a data file with plenty of columns.
I just need the first 5 but it doe not work by doing something like:
> mycols <- rep(NULL, 430) ; mycols[c(1:4)] <- NA
> read.table(myfile, skip=2, colClasses=mycols)
Any suggestions?

Thanks in advance

I think you need to read an introduction to R.
For starters, read.table returns its results as a value, which you are not
saving.
The probable answer to your question:
Read the whole file with read.table, and select columns you need, e.g.:
tab <- read.table(myfile, skip=2)[,1:5]

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Luis Ridao
Sent: Tuesday, March 15, 2011 11:53 AM
To: r-help at r-project.org
Subject: [R] How to read only specified columns from a data file

R-help,

I'm trying to read a data file with plenty of columns.
I just need the first 5 but it doe not work by doing something like:
> mycols <- rep(NULL, 430) ; mycols[c(1:4)] <- NA
> read.table(myfile, skip=2, colClasses=mycols)
Any suggestions?

Thanks in advance

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