[R] subset data.frame with constraint of many values?

[Chuck Cleland]

Dong-hyun Oh wrote:
> Dear UseRs,
> 
> Let us assume that I have data.frame named as dt.
> 
> dt is as follows:
> 
> a    b    c    d
> 1    3    4    5
> 2    3    3    2
> 1    3    4    2
> 3    2    4    5
> 4    5    3    6
> 3    2    5    7
> 2    5    7    8
> .....................
> .....................
> 
> I want to subset dt with fileds a having 2 or 3 or 4, and I wrote  
> following code.
> 
> dt[dt$a == 2 | dt$a == 3 | dt$a == 4,]
> 
> Is there more efficient way for subset?

subset(dt, a %in% 2:4)

> Thanks in advance.
> 
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Chuck Cleland, Ph.D.
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