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Use indexing by name [, namevector]
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Jeff Newmiller The ..... ..... Go Live...
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Sent from my phone. Please excuse my brevity.

Rich Shepard <rshepard@appl-ecosys.com> wrote:

I have a data frame called chemdata with this structure:

> str(chemdata)
'data.frame':	14886 obs. of 4 variables:
$ site : Factor w/ 148 levels "BC-0.5","BC-1",..: 104 145 126 115 114 128 124 2 3 3 ...
$ sampdate: Date, format: "1996-12-27" "1996-08-22" ...
$ param : Factor w/ 8 levels "As","Ca","Cl",..: 1 1 1 1 1 1 1 1 1 1 ...
$ quant : num 0.06 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 ...

I've looked in the R Cookbook and Dalgaard's intro book without finding a
way to use wildcards (e.g., like "BC-*") or explicitly witing each site ID
when subdsetting a data frame..

I need to create subsets (as data frames) based on sites, but including
all sites on each stream. For example, using the initial site factor shown
above, I want a subset containing all data for sites "BC-0.5", "BC-1".
"BC-2", "BC-3", "BC-4", "BC-5", and "BC-6".

Pointers appreciated,

Rich

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