[R] Subseting by more than one factor...

[Douglas Bates]

Fernando Henrique Ferraz Pereira da Rosa <mentus at gmx.de> writes:

>   Is it possible in R to subset a dataframe by more than one factor, all at
> once?
>      For instance, I have the dataframe: 
>  >data 
>       p1 p2 p3 p4 p5 p6 p7 p8 p9 p10      pred
>   1    0  1  0  0  0  0  0  0  0   0 0.5862069
>   4    0  0  0  0  0  0  0  0  0   1 0.5862069
>   5    0  0  0  0  0  0  1  0  0   0 0.5862069
>   6    0  0  0  0  0  0  0  1  0   0 0.5862069
>   7    0  0  1  0  0  0  0  0  0   0 0.5862069
>   9    0  0  0  0  1  0  0  0  0   0 0.5862069
>   20   0  1  1  0  0  0  0  0  0   0 0.5862069
>   22   0  1  0  0  1  0  0  0  0   0 0.5862069
>   24   0  1  0  0  0  0  1  0  0   0 0.5862069
>   25   0  1  0  0  0  0  0  1  0   0 0.5862069
>   27   0  1  0  0  0  0  0  0  0   1 0.5862069
> 
>   If I want to subset only those points that have p4 = 1, I do:
>    > subset(data,p4 == 1)
>   And that's fine. Now suppose I want to subset those that not only have p4
> = 1, but also p6 = 1.
>    I tried subset(data,p4 == 1 && p6 == 1) or subset(data,p4==1 & p6==1).


As Sundar pointed out it is the second form that you want.  When
intersecting conditions in subset() use &, not &&.

The way that you pasted the output in your message the column names
did not align with the columns.  I changed this in the part that I
quoted above.  This shows that you chose the wrong example, I think,
because that intersection is empty.  Try 

 subset(data, p2 == 1 & p3 == 1)

instead.