[R] string substitution for argument in function

[Weidong Gu]

Hi,

This may help

 a = c('one','two','three')
data.frame(eval(substitute(rbind(var,2),list(var=a))))

?substitute
?eval

Weidong Gu


On Sun, Mar 25, 2012 at 5:22 PM, Pedro Martinez
<Pedro.Martinez at senckenberg.de> wrote:
> hello,
> I want to iterate through a list of names and use each element as an
> argument in a function. For instance:
>
>> a = c('one','two','three')
>> data= c()
>> for(elem in a){data=cbind(elem = 2,data)}
>> data
>     elem elem elem
> [1,]    2    2    2
>
> instead I want 'elem' to be substituted by the string in the list. Doing
> it by hand would be:
>> data = cbind('one'=2,data)
>> data = cbind('two'=2,data)
>> data = cbind('three'=2,data)
>> data
>     'one' 'two' 'three'
> [1,]    2    2    2
>
> I guess that the clue would be in sub(),gsub(), paste() or similar but I
> didnt get it to work.
>
> I am comming from python were we woudl do something like:
>> a = ['one','two','three']
>> data = {}
>
>> for elem in a:
>>       data[elem] = 2
>
>> data
> {'three': 2, 'two': 2, 'one': 2}
>
> Thanks, Pedro
>
>
> -
> Prof. Dr. P. Martinez Arbizu
> DZMB-Forschungsinstitut Senckenberg
>
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> Germany
>
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>
> Email: pmartinez at senckenberg.de
>
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