R help - Mar 2012 - string substitution for argument in function

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

Suedstrand 44
D-26382 Wilhelmshaven
Germany

Tel: +49 (0)4421 9475-100
Fax: +49 (0)4421 9475-111

Email: pmartinez at senckenberg.de

Senckenberg Gesellschaft f?r Naturforschung
Rechtsf?higer Verein gem?? ? 22 BGB
Senckenberganlage 25
60325 Frankfurt
Direktorium: Prof. Dr. Dr. h.c. Volker Mosbrugger, Prof. Dr. Michael
T?rkay, Dr. Johannes Heilmann, Prof. Dr. Pedro Martinez Arbizu, Prof.
Dr. Georg Zizka, Prof. Dr. Uwe Fritz
Vorsitzender des Pr?sidiums: Dietmar Schmid
Aufsichtsbeh?rde: Magistrat der Stadt Frankfurt am Main (Ordnungsamt)

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
>
> Suedstrand 44
> D-26382 Wilhelmshaven
> Germany
>
> Tel: +49 (0)4421 9475-100
> Fax: +49 (0)4421 9475-111
>
> Email: pmartinez at senckenberg.de
>
> Senckenberg Gesellschaft f?r Naturforschung
> Rechtsf?higer Verein gem?? ? 22 BGB
> Senckenberganlage 25
> 60325 Frankfurt
> Direktorium: Prof. Dr. Dr. h.c. Volker Mosbrugger, Prof. Dr. Michael
> T?rkay, Dr. Johannes Heilmann, Prof. Dr. Pedro Martinez Arbizu, Prof.
> Dr. Georg Zizka, Prof. Dr. Uwe Fritz
> Vorsitzender des Pr?sidiums: Dietmar Schmid
> Aufsichtsbeh?rde: Magistrat der Stadt Frankfurt am Main (Ordnungsamt)
>
> ______________________________________________
> R-help at 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.

try this:

`names<-`(rep(2, 3), a)


On Sun, Mar 25, 2012 at 6:22 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
>
> Suedstrand 44
> D-26382 Wilhelmshaven
> Germany
>
> Tel: +49 (0)4421 9475-100
> Fax: +49 (0)4421 9475-111
>
> Email: pmartinez at senckenberg.de
>
> Senckenberg Gesellschaft f?r Naturforschung
> Rechtsf?higer Verein gem?? ? 22 BGB
> Senckenberganlage 25
> 60325 Frankfurt
> Direktorium: Prof. Dr. Dr. h.c. Volker Mosbrugger, Prof. Dr. Michael
> T?rkay, Dr. Johannes Heilmann, Prof. Dr. Pedro Martinez Arbizu, Prof.
> Dr. Georg Zizka, Prof. Dr. Uwe Fritz
> Vorsitzender des Pr?sidiums: Dietmar Schmid
> Aufsichtsbeh?rde: Magistrat der Stadt Frankfurt am Main (Ordnungsamt)
>
> ______________________________________________
> R-help at 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.



--
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O