Dear Sarah and Rolf,
Thanks for your suggestions, yes I was looking for something that'd execute
strings eval(parse) was a solution. It's extremely helpful when you want to do
something on variables generated with loops.
Juta
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
From: Rolf Turner [rolf.tur...@xtra.co.nz]
Sent: 22 August 2011 23:36
To: Sarah Goslee
Cc: Juta Kawalerowicz; r-help@r-project.org
Subject: Re: [R] looping with paste
As Sarah has said, you probably don't need to use "paste()" at all. However
if "command" is a text string containing a (syntactically correct) R command
you can execute it via
eval(parse(text=command))
E.g.:
command <- "x <- 42"
eval(parse(text=command))
x
[1] 42
I find this to be a useful trick in quite a few contexts.
cheers,
Rolf Turner
On 23/08/11 08:43, Sarah Goslee wrote:
> Juta,
>
> On Mon, Aug 22, 2011 at 4:29 PM, Juta Kawalerowicz
> <juta.kawalerow...@stx.ox.ac.uk> wrote:
>> Dear list,
>>
>> I have a spacialPolygonDataFrame where variables were unnecessarily imported
>> as factors. So I am trying to unfactor variables from
>> spatialPolygonDataFrame@data with a loop
>>
>>
>> for (i in (1:length(names( spatialPolygonDataFrame)))){
>>
>>
>> command<-paste("spatialPolygonDataFrame$names(spatialPolygonDataFrame@data[",i,"])<-as.character(
>> spatialPolygonDataFrame$names( spatialPolygonDataFrame@data[",i,"])")
>> command<-noquote(command)
>> command
>>
>> }
>>
>>
>> But I keep getting just a printout
> Yeah, you're putting together a string, not actually running any commands.
>
> Does this not work:
>
> for (i in (1:length(names( spatialPolygonDataFrame)))){
>
> spatialPolygonDataFrame$names(spatialPolygonDataFrame@data[i])<-
> as.character( spatialPolygonDataFrame$names(
> spatialPolygonDataFrame@data[i]))
>
> }
>
> Subsetting on a variable should work just fine. I don't see any need for
> paste().
>
> Sarah
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