On May 11, 2011, at 10:01 AM, David Winsemius wrote:
On May 11, 2011, at 7:55 AM, chris20 wrote:
Hi
I have dataframe with different plot numbers in and different
subplots as
letters at the end of the plot number i.e. 1a, 1b 2-1a etc.
I want to delete all rows that end in a specific letter eg...
treat<-c("1a","1b","1c","2a","2b","2c","2-1a","2-1b","2-1c")
a1<-1:9
b1<-9:1
d1<-data.frame(treat,a1,b1)
> d1[-grep("c$", d1$treat), ]
treat a1 b1
1 1a 1 9
2 1b 2 8
4 2a 4 6
5 2b 5 5
7 2-1a 7 3
8 2-1b 8 2
How do I remove all rows where treat ends in "c" ? I have tried
the usual
ways of deleting rows but nothing works.
Not sure what the usual ways are for you but negative indexing is
the usual way for me.
(Could also use subset, I suppose)
As here with grepl rather than grep:
> subset(d1, !grepl("c$", d1$treat))
treat a1 b1
1 1a 1 9
2 1b 2 8
4 2a 4 6
5 2b 5 5
7 2-1a 7 3
8 2-1b 8 2
In case you are new to grepping, the $ indicates the end of a string
and therefore 'c' will match any 'c' at the end of the string. grepl
creates a logical vector that flags matches and non-matches and the
'!' operator logically inverts it.
David Winsemius, MD
West Hartford, CT
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