[R] String manipulation

[John Fox]

Dear Luis,

How about gsub("[0-9]", "",  x) ? This assumes that x contains the character
data and not a factor, as would usually be the case in a data frame. If the
variable is really a factor, then use as.character(x) in the call to gsub().

I hope this helps,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
-------------------------------- 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Luis Ridao Cruz
> Sent: Thursday, October 20, 2005 8:24 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] String manipulation
> 
> R-help,
> 
> I have a data frame which contains a character string column 
> that is something like;
> 
> II11
> II18
> II23
> III1
> III13
> III16
> III19
> III2
> III7
> IV10
> IV11
> IV12
> IX16
> IX4
> V12
> V18
> V2
> V20
> V23
> V4
> VII14
> VII18
> VII21
> VII26
> VII28
> VII33
> VII4
> VII48
> VII5
> ....
> ....
> ....
> 
> I want to apply a function (e.g mean) by grouping according 
> to the roman part of the string, i.e,
> 
> by I
> by V
> by VII
> ...
> ...
> and so on.
> 
> I have looked at string manipulation functions (grep, 
> pmatch,,,) but I can't really get it the way I want.
> Can anyone help?
> 
> Thanks in advance.
> 
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