On Mon, 9 Mar 2009, Vadim Ogranovich wrote:
Dear R-users,
How can I detect a NULL in a recursive list?
For a regular list I could use lapply:
lapply(list(x=NULL), is.null)
$x
[1] TRUE
However that doesn't work for structures like list(list(x=NULL)). I tried
rapply but it treats NULL as a list and discards them:
rapply(list(a=1, b=list(x=NULL)), is.null)
a
FALSE
Any suggestion?
Is this what you want?
foo <- function(x) sapply(x, function(x) if (is.list(x)) foo(x) else
length(x)==0,simplify=FALSE)
foo(list(a=list(A=1:2,B=NULL), b=list(C=NULL,D=1)))
$a
$a$A
[1] FALSE
$a$B
[1] TRUE
$b
$b$C
[1] TRUE
$b$D
[1] FALSE
HTH,
Chuck
Thank you for your help,
Vadim
Note: This email is for the confidential use of the named addressee(s) only and
may contain proprietary, confidential or privileged information. If you are not
the intended recipient, you are hereby notified that any review, dissemination
or copying of this email is strictly prohibited, and to please notify the
sender immediately and destroy this email and any attachments. Email
transmission cannot be guaranteed to be secure or error-free. Jump Trading,
therefore, does not make any guarantees as to the completeness or accuracy of
this email or any attachments. This email is for informational purposes only
and does not constitute a recommendation, offer, request or solicitation of any
kind to buy, sell, subscribe, redeem or perform any type of transaction of a
financial product.
______________________________________________
R-help@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.
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
______________________________________________
R-help@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.
