R help - Feb 2008 - R equivalent of linux "cut", "paste", and "grep" ?

Hi,

What functions should I use in order to perform the following steps:

1) Load a particular column (e.g., column 5) from a csv file
2) Append the column 5 to another csv file
3) select those rows that match specific keywords in column 5

	[[alternative HTML version deleted]]

Hi,

If you are on a linux system, you can use these linux commands through 
pipe.
Otherwise :
- perl would do a great job on this.
- if you are familiar enough with SQL syntax, you can use the 
development version of the sqldf package to work on csv files as if they 
were database tables. See example 8 in http://code.google.com/p/sqldf/

Cheers,

Romain

Ng Stanley wrote:
> Hi,
>
> What functions should I use in order to perform the following steps:
>
> 1) Load a particular column (e.g., column 5) from a csv file
> 2) Append the column 5 to another csv file
> 3) select those rows that match specific keywords in column 5
>   
-- 
Mango Solutions
data analysis that delivers

Introduction to R training course :: London :: 06-07 March 2008
http://www.mango-solutions.com/services/rtraining/r_intro.html

Depending on what your final goal is, there may be a better approach,
but to do as you state below, here is one set of options:

1) use read.csv (or read.table) and use the colClasses argument to
specify keeping only column 5
2) use cbind to bind column 5 (now a data.frame) to another data.frame
(possibly read in using read.csv), this assumes that the row order
matches, merge is a possibility if they don't match.
3) use the subset command to select the rows, use the %in% operator to
compare col 5 to your list of desired values.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Ng Stanley
> Sent: Thursday, February 14, 2008 1:03 AM
> To: r-help
> Subject: [R] R equivalent of linux "cut", "paste", and
"grep" ?
> 
> Hi,
> 
> What functions should I use in order to perform the following steps:
> 
> 1) Load a particular column (e.g., column 5) from a csv file
> 2) Append the column 5 to another csv file
> 3) select those rows that match specific keywords in column 5
> 
> 	[[alternative HTML version deleted]]
> 
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