[R] select rows from data based on a vector of char strings

Applejus ielkhoury at gmail.com
Thu Apr 24 01:41:33 CEST 2008


Hi,

You are right the == doesn't work, but there's a workaround using regular
expressions:

flist<-"fun|food"
grep(flist, data$label)

will give you the vector [2 4] which are the numbers of the rows of
interest!


Dirkheld wrote:
> 
> Hi,
> 
> I have loaded a dataset in R :
> data = 
> 
> label   freq1   freq2
> news   54      35
> fun      37      21
> milk    19      7
> food     3       3
> .... etc
> 
> And I have a vector
> flist<-c("fun","food")
> 
> Now I want to use the vector 'flist' for selecting these values from
> 'data' so that I get the following dataset :
> label   freq1   freq2
> fun      37      21
> food     3       3
> 
> When I do 'data$label==flist[1]' I get 'F T F F', so it works for one item
> in the char vector flist.
> But, when I do 'data$label==flist' I get 'F F F F' while I expected 'F T F
> T'. It seems that I can't perform this action with a vector of
> charstrings? 
> 
> Is there an other way to do so?
> 
> 

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