# [R] how to find out whether a string is a factor?

David Winsemius dwinsemius at comcast.net
Tue Jul 12 16:20:46 CEST 2011

```On Jul 12, 2011, at 10:12 AM, Sam Steingold wrote:

> I have two data frames:
>> str(ysmd)
> 'data.frame':	8325 obs. of  6 variables:
> \$ X.stock                      : Factor w/ 8325 levels
> "A","AA","AA-",..: 2702 6547 4118 7664 7587 6350 3341 5640 5107
> 7589 ...
> \$ market.cap                   : num  -1.00 2.97e+10 3.54e+08 3.46e
> +08 -1.00 ...
> \$ X52.week.low                 : num  40.2 22.5 27.5 12.2 20.7 ...
> \$ X52.week.high                : num  43.3 38.2 35.1 19.2 32.7 ...
> \$ X3.month.average.daily.volume: num  154 7862250 16330 205784
> 14697 ...
> \$ X50.day.moving.average.price : num  41.8 36.3 30.5 15.2 29.9 ...
>> str(top1000)
> 'data.frame':	1000 obs. of  1 variable:
> \$ V1: Factor w/ 1000 levels "AA","AAI","AAP",..: 146 96 341 814 382
> 977 66 1 737 595 ...
>
> I want to split ysmd into two new data frames: ysmd.top1000 and
> ysmd.rest so that ysmd.top1000\$X.stock only contains factors from
> top1000\$V1 and ysmd.rest\$X.stock contains all the other factors.
>
> I should be able to just write
>
> ysmd.top1000 <- ysmd[ysmd\$X.stock "is in" top1000\$V1,]
> ysmd.rest <- ysmd[ysmd\$X.stock "not in" top1000\$V1,]
>
> but how so I check whether a string is a member of a factor?

?"%in%"

>
> --
> Sam Steingold (http://sds.podval.org/) on CentOS release 5.6 (Final)
> X 11.0.60900031
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