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:

> str(work)
 '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)




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.?

Thanks,
Matt

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