[R] split a character variable into several character variable by a character

[William Dunlap]

strsplit() is the way to do it, but if your putative
character strings come from a data.frame you need to make
sure they are really character strings and not factors
(at least in R 2.8.1).

   > d<-data.frame(name=c("Bill Dunlap", "First Last"), num=1:2)
   > d
            name num
   1 Bill Dunlap   1
   2  First Last   2
   > sapply(d,class)
        name       num 
   "factor" "integer" 
   > strsplit(d$name, " ")
   Error in strsplit(d$name, " ") : non-character argument
   > strsplit(as.character(d$name), " ")
   [[1]]
   [1] "Bill"   "Dunlap"

   [[2]]
   [1] "First" "Last" 

   > d1<-data.frame(stringsAsFactors=FALSE,name=c("Bill Dunlap", "First
Last"), num=1:2)
   > sapply(d1,class)
          name         num 
   "character"   "integer" 
   > strsplit(d1$name, " ")
   [[1]]
   [1] "Bill"   "Dunlap"

   [[2]]
   [1] "First" "Last" 

Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com 

------------------------------------------------------------------------
-
[R] split a character variable into several character variable	by a
character

Adrian Dusa dusa.adrian at gmail.com 
Fri Apr 10 15:48:53 CEST 2009

Dear Mao Jianfeng,

"r-help-owner" is not the place for help, but:
r-help at r-project.org
(CC-ed here)
In any case, strsplit() does the job, i.e.:

> unlist(strsplit("BCPy01-01", "-"))
[1] "BCPy01" "01"

You can work with the whole variable, like:
splitpop <- strsplit(df1$popcode, "-")

then access the first part with
> unlist(lapply(splitpop, "[", 1))
 [1] "BCPy01" "BCPy01" "BCPy01" "BCPy01" "BCPy01" "BCPy01" "BCPy01"
"BCPy01"
 [9] "BCPy01" "BCPy01"

and the second part with
> unlist(lapply(splitpop, "[", 2))
 [1] "01" "01" "01" "02" "02" "02" "02" "02" "02" "03"

hth,
Adrian

On Friday 10 April 2009, Mao Jianfeng wrote:
> Dear, R-lister,
>
> I have a dataframe like the followed. And, I want to split a character
> variable ("popcode", or "codetot") into several new variables. For
example,
> split "BCPy01-01" (popcode[1]) into "BCPy01" and "01". I need to know
how
> to do that. I have tried strsplit() and substring() functions. But, I
still
> can not perform the spliting.

It always helps to see exactly what you tried
and a description of how the results differ from
what you wanted to get.

>
> Any advice? Thanks in advance.
>
> df1:
> popcode     codetot   p3need
> BCPy01-01 BCPy01-01-1 100.0000
> BCPy01-01 BCPy01-01-2 100.0000
> BCPy01-01 BCPy01-01-3 100.0000
> BCPy01-02 BCPy01-02-1  92.5926
> BCPy01-02 BCPy01-02-1 100.0000
> BCPy01-02 BCPy01-02-2  92.5926
> BCPy01-02 BCPy01-02-2 100.0000
> BCPy01-02 BCPy01-02-3  92.5926
> BCPy01-02 BCPy01-02-3 100.0000
> BCPy01-03 BCPy01-03-1 100.0000
>
> Regards,
>
> Mao Jian-feng


-- 
Adrian Dusa
Romanian Social Data Archive
1, Schitu Magureanu Bd.
050025 Bucharest sector 5
Romania
Tel.:+40 21 3126618 \
     +40 21 3120210 / int.101
Fax: +40 21 3158391