Get multi-factor tabulation into a data.frame AND append a row for a grand total

2014-05-26_totals-in-df-tabulation.R

library(plyr)

## what's the best way to get tabulation of (days31, oystersOK) into a
## data.frame AND get a grand total row reflecting the expected total of 12
## months?

## related discussion has occured before here:
## http://stackoverflow.com/questions/4946873/how-do-i-add-a-row-to-a-data-frame-with-totals

## related issue open on dplyr:
## https://github.com/hadley/dplyr/issues/435

## my use case has some different elements, so I'll add it to the mix

inDat <- c("month     days31 oystersOK",
           "January   TRUE   TRUE",
           "February  FALSE  TRUE",
           "March     TRUE   TRUE",
           "April     FALSE  TRUE",
           "May       TRUE   FALSE",
           "June      FALSE  FALSE",
           "July      TRUE   FALSE",
           "August    TRUE   FALSE",
           "September FALSE  TRUE",
           "October   TRUE   TRUE",
           "November  FALSE  TRUE",
           "December  TRUE   TRUE")
inDat <- read.table(text = inDat, header = TRUE, stringsAsFactors = FALSE)

## the tabulation I want
outDat <- count(inDat, c("days31", "oystersOK"))

## two kludgy ways to add the grand total row, prior to use of, e.g. kable()
join(outDat, data.frame(freq = sum(outDat$freq)), type = "full")
rbind(outDat, c("--", "--", sum(outDat$freq)))