[R] Assigning objects to variable and variable to list in a for loop

[Johannes Radinger]

hi,

-------- Original-Nachricht --------
> Datum: Fri, 3 Feb 2012 09:04:19 -0500
> Von: Steve Lianoglou <mailinglist.honeypot at gmail.com>
> An: Johannes Radinger <JRadinger at gmx.at>
> CC: Joshua Wiley <jwiley.psych at gmail.com>, r-help at r-project.org
> Betreff: Re: [R] Assigning objects to variable and variable to list in a for loop

> Hi,
> 
> On Fri, Feb 3, 2012 at 8:00 AM, Johannes Radinger <JRadinger at gmx.at>
> wrote:
> > Hello,
> >
> > I tried to use the lapply approach, but I am not sure how to
> > se it correctly for my task. Here I just want to give an short
> > script which explains how my data structure looks like. It also
> > contains the second approach with a for loop which is working but
> > there is the question of how assining the result to a list.
> >
> > I think the script is somehow self explaining. Anyway what is called
> > res is in "reality" rather an object (maxent) than a single value (thats
> why I need the list)
> >
> > #create data
> > cat <- c("A","A","B","C","C")
> > value <- runif(5)
> > df <- data.frame(cat,value)
> >
> > # get names of cat with more than 1 entries
> > select.cat <- names(table(df$cat)[table(df$cat)>1])
> > cat.list <- as.list(select.cat)
> >
> > ###### lapply approach ####
> > fun = function(x){
> >        sub.df<- subset(df,cat ==  x)
> >        # here are other operations, result is an object
> >        res <- sub.df
> >        res #here just a single value but in the long script it is an
> object
> >        }
> > reslist <- lapply(cat.list, fun(unlist(cat.list)))
> 
> I think you may need to thumb through the ?lapply documentation a bit
> more. lapply will feed ever element in the list you are iterating over
> into the first argument of the function you have in lapply's second
> argument, so you would rather have something like:
> 
> reslist <- lapply(cat.list, fun)

Thank you! Thats it...fun doesn't need any argument to be specified as it is autmatically feed in as you said..

/johannes

> 
> Assuming that `fun` only needs one element from cat.list to do its duty
> ...
> 
> -steve
> 
> -- 
> Steve Lianoglou
> Graduate Student: Computational Systems Biology
>  | Memorial Sloan-Kettering Cancer Center
>  | Weill Medical College of Cornell University
> Contact Info: http://cbio.mskcc.org/~lianos/contact

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