On Fri, 28 Oct 2011, Rich Shepard wrote:
May not be until Monday that I return with results on this effort as I'm
going to be carfully checking and documenting each step and its results.
Dan, et al.:
Got it working properly now. Took a different approach after re-reading
the source data into an R data frame.
I applied the subset() function to extract all rows for a single stream
(all commands are on a single line in emacs but wrap when copied into
alpine):
burns <- subset(chemdata, stream == 'BurnsCrk', select = c(site, sampdate,
param, quant), drop = T)
Then I applied the reshape2 melt() function:
burns.melt <- melt(burns, id.vars = c('site', 'sampdate', 'param'))
which produced this data frame:
head(burns.melt)
site sampdate param variable value
1 BC-0.5 1996-06-02 OH quant NA
2 BC-0.5 1996-06-02 SO4 quant 194.00
3 BC-0.5 1996-06-02 TDS quant 530.00
4 BC-0.5 1996-06-02 TSS quant NA
5 BC-0.5 1996-04-19 As quant 0.01
6 BC-1.5 1996-09-19 As quant NA
Then the reshape2 dcast() function produced the desired results:
burns.cast <- dcast(burns.melt, site + sampdate ~ param)
head(burns.cast)
site sampdate Acid Ag Al Alk-HO Alk-Tot As Ba Be Bo CO3 Ca Cd
1 BC-0.5 1996-04-19 NA NA 0.07 NA 162 0.01 0.18 NA NA NA 76.56 NA
2 BC-0.5 1996-05-21 NA NA NA NA 152 NA NA NA NA NA NA NA
3 BC-0.5 1996-06-02 NA NA NA NA 212 NA NA NA NA NA NA NA
4 BC-1 1988-06-26 NA NA NA NA NA 0.00 NA NA NA NA NA NA
5 BC-1 1988-07-30 NA NA NA NA NA 0.00 NA NA NA NA NA NA
6 BC-1 1989-05-15 NA NA NA NA NA 0.00 NA NA NA NA NA NA
et cetera.
Thank you all for your patient help. Now I should be able to produce
scatter plots and run linear regressions on selected parameter pairs by site
and date.
Carpe weekend, all,
Rich
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