[R] Differing rows in two data.frames?

Jesse Brown jesse.r.brown at lmco.com
Tue Aug 18 13:32:43 CEST 2009

Mark Knecht wrote:
> On Mon, Aug 17, 2009 at 2:25 PM, Mark Knecht<markknecht at gmail.com> wrote:
>> Hi,
>>   What commands would I look at to compare row-by-row two data frames
>> of the same size and print out any differences between the two?
>> Thanks,
>> Mark
> So I got an answer using the following code:
> XXX = cbind(SystemWithCP, SystemWithoutCP)
> head(XXX)
> names(XXX)[14] = "NewPLPos"
> head(XXX)
> YYY = subset(XXX, XXX$PL_Pos != XXX$NewPLPos)
> write.csv(YYY, "C:\\Dave1.csv")
> This works (I suppose) because the two data.frames are exactly the
> same size. Seems like there probably a much better way to do it but
> this seems to work.
> - Mark
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Sorry if this ends up being a dup, I forgot to include the list in the reply.

yyy <- SystemWithCP - SystemWithoutCP
yyy[apply(yyy,1,function(x) any(x != 0))]

This gives you the row they differ on and the column that is different, but not the actual values.
You might also try a modification on what you have above

yyy <- subset(cbind(SystemWithCP,SystemWithoutCP), SystemWithCP$PL_Pos != SystemWithoutCP$PL_Pos)

Which gives you the same as your example without the modified names.
I'm not entirely clear on if you need to retain the values or just that they are different.

- Jesse

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