R help - Apr 2008 - select rows from data based on a vector of char strings

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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On 4/23/2008 3:13 AM, 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?
newdata <- subset(data, label %in% flist)

?subset
?is.element

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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?
> 
> 
-- 
View this message in context:
http://www.nabble.com/select-rows-from-data-based-on-a-vector-of-char-strings-tp16832735p16834876.html
Sent from the R help mailing list archive at Nabble.com.

Try this,

x="label   freq1   freq2
news   54      35
fun      37      21
milk    19      7
food     3       3"

yourdata=read.table(textConnection(x),header=TRUE)
attached(yourdata)
flist<-c("fun","food")

yourdata[label %in% flist,]


I hope this helps,


Jorge



On Wed, Apr 23, 2008 at 3:13 AM, Dirkheld <dirk.bollen@soc.kuleuven.be>
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?
>
> --
> View this message in context:
>
http://www.nabble.com/select-rows-from-data-based-on-a-vector-of-char-strings-tp16832735p16832735.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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
> and provide commented, minimal, self-contained, reproducible code.
>
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