[R] simple question on picking out some rows of a matrix/data frame
Spencer Graves
spencer.graves at pdf.com
Tue Feb 10 01:15:41 CET 2004
One alternative that I use is illustrated in the following examples:
> DF[DF$x==DF$y, ]
x y z
1 -1 -1 a
4 1 1 d
>
> sel <- (DF$x != DF$y)
> DF[sel,]
x y z
2 1 -1 b
3 -1 1 c
hope this help.
spencer graves
Douglas Bates wrote:
>"subset" will do the selection. If you really want a matrix for the
>result you will need to coerce it using "as.matrix".
>
>Roger Levy <rog at stanford.edu> writes:
>
>
>
>>I have a simple question about matrix/data frame manipulation. I have
>>a data frame that looks a something like this
>>
>> X Y Z
>> 1 0 "apples"
>> -1 -1 "oranges"
>> ...
>> 0 -1 "bananas"
>>
>>and I'd like to pull out all the rows for which X and Y are (un)equal
>>into a submatrix.
>>
>>How can I do that?
>>
>>Many thanks,
>>
>>Roger Levy
>>
>>
>
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