Hi,
Using your example (note I called the list 'z')...
z <-list(a = seq(1:5), b = seq(10:20))
I picture lapply as extracting each element of z like this z[[i]] - the `[[`
extracts the ith value from the context of residing in a list - hence it's name
is 'lost' in the new context. That's different than z[i] which extracts a list
of elements. Try..
z[['a']] vs. z['a']
As an alternative and depending upon what you really want to do, you could
iterate through the names of the list, and pass the list as a parameter.
r <- lapply(names(z),
function(nm, dat = NULL){
sprintf("%s has %i elements", nm, length(dat[[nm]]) )
},
dat = z)
r
[[1]]
[1] "a has 5 elements"
[[2]]
[1] "b has 11 elements"
Ben
> On Feb 25, 2016, at 4:27 PM, Mohammad Tanvir Ahamed via R-help
> <r-help@r-project.org> wrote:
>
> Hello,
>
> I want to get object name of a list inside lapply
>
>> c<-list(a=seq(1:5),b=seq(10:20))
>> lapply(c,names)
> $a
> NULL
>
> $b
> NULL
>
> Why NULL ?
>
> but i am expecting the names of object . Any help will be appreciated .
>
> I want to grab the names of object inside lapply for further process.
>
> Thanks .
>
>
> Tanvir Ahamed
> Göteborg, Sweden | mashra...@yahoo.com
>
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