sessionInfo()
## R version 2.15.1 (2012-06-22)
## Platform: i386-apple-darwin9.8.0/i386 (32-bit)
##
## locale:
## [1] C/en_US.UTF-8/C/C/C/C
##
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets  methods   base
##
## other attached packages:
## [1] knitr_0.8
##
## loaded via a namespace (and not attached):
## [1] digest_0.5.2   evaluate_0.4.2 formatR_0.6    plyr_1.7.1
## [5] stringr_0.6.1  tools_2.15.1