[R] list manipulation

From: Thompson, David (MNR) <David.John.Thompson_at_ontario.ca>
Date: Tue, 06 May 2008 14:35:54 -0400


Hello,

I have a set of one-liners (many thanks to previous responses from this list) that I use to look at newly imported data sets with functions like dim(), names(), str(), etc. within lapply(). Generally, these commands work for me but, I am apparently still missing some aspect of list manipulation. I don't understand why I get a set of NULL list elements at the end of each output as demonstrated below. How can I generate this (and similar) result(s) without all the trailing NULLs?

> lapply(ls(pattern='bn'), function(x) cat(x, dim(get(x)), "\t", names(get(x)), "\n"))
bn1993 2885 11 oplt rplt rsiz tree bd ht oaz odst raz rdst spr bn1994 3158 7 oplt tree bd ht spr stat dam

bn1995 734 7     oplt tree bd ht spr stat dam 
bn1996 293 7     oplt tree bd ht spr stat dam 
bn1997 264 7     oplt tree bd ht spr stat dam 
bn1998 768 7     oplt tree bd ht spr stat dam 
bn1999 654 7     oplt tree bd ht dbh stat dam 
bn2003 1407 9 oplt tree bd94 ht94 ht99 ht02 ht03 stat dam
[[1]]

NULL
[[2]]

NULL
[[3]]

NULL
[[4]]

NULL
[[5]]

NULL
[[6]]

NULL
[[7]]

NULL
[[8]]

NULL Thanx, DaveT.

Silviculture Data Analyst
Ontario Forest Research Institute
Ontario Ministry of Natural Resources
david.john.thompson_at_ontario.ca
http://ofri.mnr.gov.on.ca

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