[R] extracting from a data.frame

[Sean Davis]

Look at ?subset.

Sean

On Jan 28, 2005, at 1:26 PM, dax42 wrote:

> Hi,
>
> I am sorry for this simple question, but... How do I extract something 
> from a data.frame?
> The following is my Problem:
> I have got a dataframe "a" with various columns. One of those columns 
> is called V3 and contains elements of the following levels:
>
> > levels(a$V3)
>  [1] "C"   "CA"  "CB"  "CD"  "CD1" "CD2" "CE"  "CE1" "CE2" "CE3" "CG"
> [12] "CG1" "CG2" "CH2" "CZ"  "CZ2" "CZ3" "N"   "ND1" "ND2" "NE"  "NE1"
> [23] "NE2" "NH1" "NH2" "NZ"  "O"   "OD1" "OD2" "OE1" "OE2" "OG"  "OG1"
> [34] "OH"  "OXT" "SD"  "SG"
>
> Now I would like to get all rows of a, that have the value "O" in V3.
> I tried a lot of different combinations of [... but I couldn't make it.
>
> Any ideas?
> Thanks a lot!
> Dax.
>
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