Dear all --
I have a data frame containing data related to heat gain through
windows. The general form is ...
Key ProfA IAC <many other numeric columns>
AAA 0 .7
AAA 10 .6
AAA 0 .66
AAA 20 .45
(more AAA rows)
(then AAB rows)
'Key' identifies the physical configuration ... rows with a given Key
contain data for same window under various conditions.
I want to add a column IAC0 containing, for each Key, the mean IAC of
all rows with ProfA == 0.
The general approach I think I need is approximately (the following
is not known to run) --
1) XS<-subset( X, ProfA < .01) to get the ProfA == 0 rows. This
could be done implicitly as part of step 2, I suppose.
2) X0<-aggregate( XS[,"IAC"], by=list( Key=XS$Key), mean)
3) XF<-merge( X, X0, by="Key")
4) Change new col name to "IAC0" (see Question 2).
Question 1: Is this a reasonable way to solve my problem?
Question 2: The aggregate() result has 2 columns: "Key" and
"x". Can the name of the mean column be specified (short of
renaming after the fact)? All the aggregate() examples (e.g. in
help()) elegantly produce the "right result" with nicely named
columns etc. I can't seem to make things work so smoothly.
Thanks!
Chip Barnaby
---------------------------------------------------------
Chip Barnaby [EMAIL PROTECTED]
Vice President of Research
Wrightsoft Corp. 781-862-8719 x118 voice
131 Hartwell Ave 781-861-2058 fax
Lexington, MA 02421 www.wrightsoft.com
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