[R] Subset dataframe based on condition
Tony Plate
tplate at acm.org
Mon Apr 17 20:46:45 CEST 2006
Works OK for me:
> x <- data.frame(a=10^(-2:7), b=10^(10:1))
> subset(x, a > 1)
a b
4 1e+01 1e+07
5 1e+02 1e+06
6 1e+03 1e+05
7 1e+04 1e+04
8 1e+05 1e+03
9 1e+06 1e+02
10 1e+07 1e+01
> subset(x, a > 1 & b < a)
a b
8 1e+05 1000
9 1e+06 100
10 1e+07 10
>
Do you get all "numeric" for the following?
> sapply(x, class)
a b
"numeric" "numeric"
>
If not, then your data frame is probably encoding the information in
some way that you don't want (though if it was as factors, I would have
expected a warning from the comparison operator).
You might get more help by distilling your problem to a simple example
that can be tried out by others.
-- Tony Plate
Sachin J wrote:
> Hi,
>
> I am trying to extract subset of data from my original data frame
> based on some condition. For example : (mydf -original data frame, submydf
> - subset dada frame)
>
> >submydf = subset(mydf, a > 1 & b <= a),
>
> here column a contains values ranging from 0.01 to 100000. I want to
> extract only those matching condition 1 i.e a > . But when i execute
> this command it is not giving me appropriate result. The subset df -
> submydf contains rows with 0.01 also. Please help me to resolve this
> problem.
>
> Thanks in advance.
>
> Sachin
>
>
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