[R] Strange "rownames"

[Peter Ehlers]

Zhang Jian wrote:
> I find one row in my large dataset. But when I use the "rownames" for the
> data on the 100,000 row, the result show nothing.
> I try it by the following example, it still likes that.
> 
>> tst[rownames(tst)==100000,]
> [1] x y
> <0 rows> (or 0-length row.names)
> 
> ##############
> 
>> tst=data.frame(x=1:200000,y=200000:1)
>> tst[rownames(tst)==1,]
>   x      y
> 1 1 200000
>> tst[rownames(tst)==10000,]
>           x      y
> 10000 10000 190001
>> tst[rownames(tst)==100000,]
> [1] x y
> <0 rows> (or 0-length row.names)
>> tst[100000,]
>             x      y
> 100000 100000 100001
> 
> Is it a bug for R?

No, it's your use of a non-character rowname, viz

 > tst[rownames(tst)=="100000",]
             x      y
100000 100000 100001

Hints:

 > 1000
[1] 1000

 > 100000
[1] 1e+05

 > options(scipen=10)
 > tst[rownames(tst)==100000,]
             x      y
100000 100000 100001

Perhaps R should do a bit less coercing.

  -Peter Ehlers

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-- 
Peter Ehlers
University of Calgary