Overview of how/why to reshape data in R from "wide" (spreadsheet-like) to "long" (database-like) and back.
Focuses on Hadley Wickham's reshape2 package and uses state population data from the 2010 U.S. Census. Also demonstrates use of dcast() to replace table(), etc. to generate crosstabs from a sample market research consumer survey.
Presented at the April 2011 meeting of the Greater Boston useR Group.