Stuff to fill in

[franknarf1]

Rename work to "navigating data", leave "approximation et al" in "work"

• [x] "Input and output"
  • [x] "Managing data types"
• [x] "Exploring data"
  • [x] "Summary statistics" maybe this should appear sooner or later than it does
• [x] Joins
  • [x] Cross join needs to explain CJ before the more complicated CJ.dt
  • [x] "Advanced joins" needs cleanup... maybe expansion instead
• [x] "Managing multiple data sets" / structuring data -- maybe this should be much sooner..? move cross join and update join here?
  • [x] "Expanding rows" (to include missing levels) -- note where else this comes up and linkify

[franknarf1]

Things to warn about:

• it may look like an NA but really be Inf: min of an empty date vector, like z = min(Sys.Date()[0L]) prints as NA but doesn't pass is.na. guess i need to sanitize with replace(z, !is.finite(z), z[NA_integer_])

[franknarf1]

Finding answers -- help.start() -> Resources -> R-FAQ

Finding packages -- most serious stats pkgs seem to have entries in the r journal (analogous to the stata journal) or similar stats-software publications like jstatsoft

[franknarf1]

which(), which(., arr.ind=TRUE) and DT[i, which=TRUE] need to be covered somewhere

[franknarf1]

Maybe formula notation, ref from http://stackoverflow.com/documentation/r/1061/formula