[R] Casting lists to data.frames, analog to SAS
dwinsemius at comcast.net
Wed Jan 14 22:14:05 CET 2009
On Jan 14, 2009, at 3:56 PM, Matthew Pettis wrote:
> <Resubmitting: Told I had a problem with a character set -- now
> submitting in plain text>
> I have a specific question and a general question.
> Specific Question: I want to do an analysis on a data frame by 2 or
> more class variables (i.e., use 2 or more columns in a dataframe to do
> statistical classing). Coming from SAS, I'm used to being able to
> take a data set and have the output of the analysis in a dataset for
> further manipulation. I have a data set with vote totals, with one
> column being the office name being voted on, and the other being the
> party of the candidate. My votes are in the column "vc.n". I did the
> analysis I want with:
> work <- by(sd62[,"vc.n"], sd62[,c("office.nm","party.abbr")], sum)
> the str() output of work looks like:
> 'by' int [1:9, 1:11] NA 30 NA NA 0 0 0 NA 33 25678 ...
> - attr(*, "dimnames")=List of 2
> ..$ office.nm : chr [1:9] "ATTORNEY GENERAL" "GOVERNOR & LT
> GOVERNOR" "SECRETARY OF STATE" "STATE AUDITOR" ...
> ..$ party.abbr: chr [1:11] "CP" "DFL" "DFL2" "GP" ...
> - attr(*, "call")= language by.default(data = sd62[, "vc.n"], INDICES
> = sd62[, c("office.nm", "party.abbr")], FUN = sum)
When I use as.data.frame.table on a similarly constructed object I get:
> as.data.frame.table(with(warpbreaks, by(breaks, list(wool,
Var1 Var2 Freq
1 A L 401
2 B L 254
3 A M 216
4 B M 259
5 A H 221
6 B H 169
> work is now a list. I'd really like to have work be a data frame with
> 3 columns: The rows of the first two columns show the office and party
> levels being considered, and the third being the sum of the votes for
> that level combination. How do I cast this list/output into a data
> frame? using 'as.data.frame' doesn't work.
> General Question: I assume the answer to the specific question is
> dependent on my understanding list objects and accessing their
> attributes. Can anyone point me to a good, throrough treatment of
> these R topics? Specifically how to read and interpret the output of
> the str(), and attributes() function, how to extract the values of the
> 'by' output object into a data frame, etc.?
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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