[R] Simple column selection question- which and character lists

Erik Iverson eiverson at NMDP.ORG
Mon Aug 31 19:15:35 CEST 2009

1) Don't call your data.frame "data".  I will call my "example" one "df".

2) If you want the columns NOT in names.species.bio.18, which is what you said, then the answer is: 

df[!names(df) %in% names.species.bio.18]


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of AllenL
Sent: Monday, August 31, 2009 11:40 AM
To: r-help at r-project.org
Subject: [R] Simple column selection question- which and character lists

Dear R-list,
Seems simple but have tried multiple approaches, no luck.

I have a list of column names:

I want to select the column numbers which correspond to these names in my
data frame:

+[1] 75 76
+Warning message:
+In cols == names.species.bio.18 :
+  longer object length is not a multiple of shorter object length

So I get the first two hits and then it trips an error message.

What is  >which doing? Why does it seem to have trouble with vectors of
My goal is to output the column names/indices which correspond to the
columns NOT in the above list, but that is simple once I can find out what
they are.


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