hadley/adv-r — pull request #239 by ajschumacher (2014-01-11 04:56:13+00:00)
Title: typo, and correct arg to read.csv is na.strings

one of two consecutive "using"s removed

From the help for read.csv:
na.strings
a character vector of strings which are to be interpreted as NA values. Blank fields are also considered to be missing values in logical, integer, numeric and complex fields.