> -----Original Message-----
> From: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] On Behalf Of Mark Na
> Sent: Tuesday, June 16, 2009 11:27 AM
> To: r-help@r-project.org
> Subject: [R] How to subset my dataframe? (a bit tricky)
>
> Hi R-helpers,
>
> I would like to subset my dataframe, keeping only those rows which
> satisfy the following conditions:
>
> 1) the string "dnv" is found in at least one column;
> 2) the value in the column previous to the one "dnv" is found
> in is not "0"
Suppose your data.frame is called 'd'. Then try looping over
its columns:
keep <- rep(FALSE, nrow(d))
if (ncol(d)>2) for(i in 3:ncol(d)) keep <- keep | ( d[,i]=="drv" &
d[,i-1]!="0")
so
d[keep,]
is the subset you want.
Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com
>
> Here's what my data look like:
>
> POND_ID 2009-05-07 2009-05-15 2009-05-21 2009-05-28 2009-06-04
>
> 4 101 0.15 0 dnv dnv dnv
> 7 102 0 dnv dnv dnv dnv
> 87 103 0.15 dnv 1 1 1
> 99 104 dnv 0.25 1 1 0.75
>
> So, for above example, the new dataframe would not contain POND_ID 101
> or 102 (because there is a 0 before the dnv) but it WOULD contain
> POND_ID 103 (because there is a 0.15 before the dnv) and 104 (because
> dnv occurs in the first column, so cannot be preceded by a 0).
>
> One extra twist: I would like to retain rows in the new dataframe
> which satisfy the above conditions even if they also have a "0" then
> "dnv" sequence preceding or following the "problem" , e.g., the
> following rows would be retained in the new dataframe
>
> POND_ID 2009-05-07 2009-05-15 2009-05-21 2009-05-28 2009-06-04
>
> 100 105 0.15 dnv 1 0 dnv
> 101 106 0 dnv 1 0.15 dnv
>
> Thanks in advance for any help you might provide.
>
> (I hope I've provided enough of an example; I could also provide a
> .csv file if that would help.)
>
> Mark Na
>
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>
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