[R] Extract information from the names of a list within lapply

Joshua Wiley jwiley.psych at gmail.com
Fri Apr 15 20:22:19 CEST 2011

Hi Jun,

On Fri, Apr 15, 2011 at 11:14 AM, Jun Shen <jun.shen.ut at gmail.com> wrote:
> Dear list,
> I want to loop over a list through lapply and at the same time I want to
> extract some information from the names of the list elements. lapply does
> not seem to carry the names. Is there anyway to access the names of a list
> within lapply? Thanks.

Not in the way you are probably trying to do it, but consider:

## 1 (what you are probably doing)
lapply(mtcars, mean)
## 2 (an alternative)
lapply(colnames(mtcars), function(x) {cat(x, fill = TRUE); mean(mtcars[, x])})

The main downside of #2 is that it takes more code, and the resulting
output is not named.  However, it gives you all the flexibility you



> Jun
>        [[alternative HTML version deleted]]
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Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles

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