R help - May 2008 - use list elements to subtract values from the dataframe

Hi,

I have a dataframe wf existing of a header with different labels and beneath
the values of those labels :
wf:
label1  label2  ...
0,45    0,21
0,10    0,45 
....      ....

I have a list
fl <- c("label2","label3",..)

Isn't possible to use the list elements in the list in order to subtract
values from the dataframe? like :
wf$fl[[1]] 
When I do in R I get :NULL
fl[[1]] gives  "label2"  so no problem here...

While wf$label1 works fine.



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Dirkheld <dirk.bollen <at> soc.kuleuven.be>
writes:
> I have a dataframe wf existing of a header with different labels and
beneath
> the values of those labels :
> wf:
> label1  label2  ...
> 0,45    0,21
> 0,10    0,45 
> ....      ....
> 
> I have a list
> fl <- c("label2","label3",..)
> 
> Isn't possible to use the list elements in the list in order to
subtract
> values from the dataframe? like :
> wf$fl[[1]] 
> When I do in R I get :NULL
> fl[[1]] gives  "label2"  so no problem here...
> 
> While wf$label1 works fine.
> 

Dirk, possibly not the most elegant solution, but I would use:

f1.indices = match(f1, names(wf))
wf[f1.indices[1]]

Good luck,

-Ash.

---

-----
Ashish Ranpura
Institute of Cognitive Neuroscience
University College London
17 Queen Square
London WC1N 3AR

tel: +44 (20) 7679 1126
web: http://www.icn.ucl.ac.uk

What you want is:

wf[[fl[1]]]

'fl' is a vector, so you should only be using a single '[' for
indexing.

On Wed, May 7, 2008 at 3:20 AM, Dirkheld <dirk.bollen at soc.kuleuven.be>
wrote:
>
> Hi,
>
> I have a dataframe wf existing of a header with different labels and
beneath
> the values of those labels :
> wf:
> label1  label2  ...
> 0,45    0,21
> 0,10    0,45
> ....      ....
>
> I have a list
> fl <- c("label2","label3",..)
>
> Isn't possible to use the list elements in the list in order to
subtract
> values from the dataframe? like :
> wf$fl[[1]]
> When I do in R I get :NULL
> fl[[1]] gives  "label2"  so no problem here...
>
> While wf$label1 works fine.
>
>
>
> --
> View this message in context:
http://www.nabble.com/use-list-elements-to-subtract-values-from-the-dataframe-tp17098923p17098923.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

Try
get(paste("wf$",fl[[1]],sep=""))

See ?get

Julian


Dirkheld wrote:
> Hi,
> 
> I have a dataframe wf existing of a header with different labels and
beneath
> the values of those labels :
> wf:
> label1  label2  ...
> 0,45    0,21
> 0,10    0,45 
> ....      ....
> 
> I have a list
> fl <- c("label2","label3",..)
> 
> Isn't possible to use the list elements in the list in order to
subtract
> values from the dataframe? like :
> wf$fl[[1]] 
> When I do in R I get :NULL
> fl[[1]] gives  "label2"  so no problem here...
> 
> While wf$label1 works fine.
> 
> 
>