There must be a better way to select the rows after 22-Apr-2004 and
before 01-Sep-2004 with a temperature below 65 than this:
> before2sw1 <- subset(energy.data, as.Date(start, format="%d-%b-%y") <
as.Date("01-Sep-04", format = "%d-%b-%y"))
> before2sw2 <- subset(before2sw1, as.Date(start, format="%d-%b-%y") >=
as.Date("22-Apr-04", format = "%d-%b-%y"), select=c(therms,temp,days))
> before2sw <- subset(before2sw2, temp < 65)
Is it also possible to combine in this step:
attach(before2sw)
before2sw.HDD <- therms / (65 - temp) * days
My data looks like this:
> head(energy.data)
start therms gas KWHs elect temp days
1 10-Jun-98 9 16.84 613 63.80 75 40
2 20-Jul-98 6 15.29 721 74.21 76 29
3 18-Aug-98 7 15.73 597 62.22 76 29
4 16-Sep-98 42 35.81 460 43.98 70 33
5 19-Oct-98 105 77.28 314 31.45 57 29
6 17-Nov-98 106 77.01 342 33.86 48 30
>
Thanks for your suggestions and advice. I'm continuing to enjoy learning
R.
-Kevin
Kevin Zembower
Internet Services Group manager
Center for Communication Programs
Bloomberg School of Public Health
Johns Hopkins University
111 Market Place, Suite 310
Baltimore, Maryland 21202
410-659-6139
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