Next time you include a data frame that has spaces in the fields, please
consider using 'dput' to provided the data.  It is hard to read in
otherwise.

Will this do it:

> x <- read.table(textConnection("                     DESCRIPTION    prix
quantity
+ 1                     'CORN Jul/10'    -1.5        0
+ 2                     'CORN May/10' -1082.0       -3
+ 3      'ROBUSTA COFFEE (10) Jul/10' 11084.0        8
+ 4                 'SOYBEANS Jul/10'  1983.5        2
+ 5 'SPCL HIGH GRADE ZINC USD Jul/10' -2464.0       -1
+ 6        'STANDARD LEAD USD Aug/10'  -118.0        0"), header=TRUE, as.is
=TRUE)
.>
> x$DESCRIPTION <- sub("USD [[:alpha:]]+/[[:digit:]]+", "USD",
x$DESCRIPTION)
>
> x
                 DESCRIPTION    prix quantity
1                CORN Jul/10    -1.5        0
2                CORN May/10 -1082.0       -3
3 ROBUSTA COFFEE (10) Jul/10 11084.0        8
4            SOYBEANS Jul/10  1983.5        2
5   SPCL HIGH GRADE ZINC USD -2464.0       -1
6          STANDARD LEAD USD  -118.0        0


On Wed, Apr 28, 2010 at 7:13 AM, arnaud Gaboury <arnaud.gaboury@gmail.com>wrote:

> Dear group,
>
> I need to modify some characters in a data frame. I want to use gsub and
> the
> regex functionalities to do this.
>
> Here is the data frame (df):
>
>                      DESCRIPTION    prix quantity
> 1                     CORN Jul/10    -1.5        0
> 2                     CORN May/10 -1082.0       -3
> 3      ROBUSTA COFFEE (10) Jul/10 11084.0        8
> 4                 SOYBEANS Jul/10  1983.5        2
> 5 SPCL HIGH GRADE ZINC USD Jul/10 -2464.0       -1
> 6        STANDARD LEAD USD Aug/10  -118.0        0
>
>
> For each df$DESCRIPTION element containing "USD" I want to remove the last
> part of it(i.e Jul/10, or Aug/10...).
> I was thinking of something like that:
>
> >Df$DESCRIPTION<-gsub("USD","new name whithout last part",df$DESCRIPTION)
>
> to get this following result:
>
>
>                      DESCRIPTION    prix quantity
> 1                     CORN Jul/10    -1.5        0
> 2                     CORN May/10 -1082.0       -3
> 3      ROBUSTA COFFEE (10) Jul/10 11084.0        8
> 4                 SOYBEANS Jul/10  1983.5        2
> 5        SPCL HIGH GRADE ZINC USD -2464.0       -1
> 6               STANDARD LEAD USD  -118.0        0
>
> My problem is that I have no idea how to write the regular expression in my
> command line.
>
> Any help would be appreciated.
>
> ______________________________________________
> R-help@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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

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