[R] Alternative method for range-matching within 2 nested loops in R?

[Bert Gunter]

Perhaps: ?findInterval

(you may need to do some type conversion first)

-- Bert

On Sat, Jul 27, 2013 at 3:28 PM, John Helly <hellyj at ucsd.edu> wrote:
> Hi.
>
> I've been puzzling about how to replace the nested loops below. The idea is
> that the B dataframe has rows with a posix datetime and the C dataframes has
> posix Start and End times.  I want to assign a value to the observations in
> B based in intersecting the appropriate time-interval in C.  I haven't been
> able to discern a more efficient way to do this.  Any suggestions would be
> most appreciated.
>
> brows = dim(B)[1]
> mrows = dim(C)[1]
>
> for (i in 1:brows ) {
>     for (j in 1:mrows ) {
>         if (B$Datetime[i] >= C$DT_Start[j] & B$Datetime<=C$DT_End[j]){
>             B$Site[i] = C$Proximity[j]
>         }
>     }
> }
>
> --
> John Helly, University of California, San Diego / San Diego Supercomputer
> Center / Scripps Institution of Oceanography / 760 840 8660 mobile /
> stonesteps (Skype) / stonesteps7 (iChat) / http://www.sdsc.edu/~hellyj
>
>
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>



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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