[Rd] lapply(NULL, ...) returns empty list

Vadim Organovich vogranovich at jumptrading.com
Thu Sep 4 23:01:46 CEST 2008


Dear R-devel,

Is there a reason that lapply(NULL, ...) returns the empty list, rather than NULL? It seems intuitive to expect the latter, and rather counterintuitive that lapply(list(), ... ) returns the same value as lapply(NULL, ...).

> lapply(list(), function(x) 1)
list()
>  lapply(NULL, function(x) 1)
list()
> version
               _
platform       i386-pc-mingw32
arch           i386
os             mingw32
system         i386, mingw32
status
major          2
minor          7.1
year           2008
month          06
day            23
svn rev        45970
language       R
version.string R version 2.7.1 (2008-06-23)
>

Regards,
Vadim

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