R help - May 2009 - is there a way to read a specific column from a txt file

Sometimes, it is too costly to read the whole data file into R.
I am looking for solution in scan() and read.Lines() but don't they work.
Thank you so much!
-- 
=============================WenSui Liu
Acquisition Risk, Chase
Blog   : statcompute.spaces.live.com

Tough Times Never Last. But Tough People Do.  - Robert Schuller

The sqldf package can read in a column without reading the
entire file into R.  It will automatically set up a database for you
read the file into the database (all this without going through R)
and then it will extract the column you want.
You will need two statements. One to define which
file to use and one to read in the file and extract the column.
See example 6b on the sqldf home page: http://sqldf.googlecode.com

On Sun, May 3, 2009 at 1:36 PM, Wensui Liu <liuwensui at gmail.com>
wrote:
> Sometimes, it is too costly to read the whole data file into R.
> I am looking for solution in scan() and read.Lines() but don't they
work.
> Thank you so much!
> --
> =============================> WenSui Liu
> Acquisition Risk, Chase
> Blog ? : statcompute.spaces.live.com
>
> Tough Times Never Last. But Tough People Do. ?- Robert Schuller
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

On Sun, May 3, 2009 at 6:36 PM, Wensui Liu <liuwensui at gmail.com>
wrote:
> Sometimes, it is too costly to read the whole data file into R.
> I am looking for solution in scan() and read.Lines() but don't they
work.
Try the following (assuming a 3 columns data file):

mydata <-
read.table(file="myfile",header=T,colClasses=c(NA,"NULL",NA))

"NULL" indicates the column to be omitted.

Hope this helps you,

Paul