usingR
https://www.buffalo.edu/content/dam/www/ccr/pdfs/hswshp2013/usingR.pdf
21 Jan 2008:
John Braun gave valuable help with proofreading, and provided several of the data sets and a number of the exercises. ... c(Andreas=178, John=185, Jeff=183)[c("John","Jeff")]. John Jeff. 185 183. 14. Be warned that y[y==NA] <- 0 leaves y unchanged.