JV ch. 4

although this chapter is titled 'multivariate data', most of it is spent filling in the gaps and expanding your understanding of how R deals with data in the form of lists and data frames. [although we haven't really talked about it, you've been using data frames since you first started using attach().] also of note will be the additional practice you will get (and skills you will develop) in making plots. although it may seem insanely hard at first, once you get the hang of it, R will allow you to make some really nice plots with comparably little effort (at least in comparison to at least some other statistical graphing packages that i'm familiar with).

as to what to focus on -- at the beginning of the chapter the author again spends some time showing you how to make various tables, which, as i've indicated before, i think may be something better left to spreadsheets. at least at the beginning.

the end of section 4.1 gives you a nice explanation of high- versus low- level plotting features, and some examples of additional plotting options.

section 4.2 is a tedious but useful (and necessary) breakdown of some of the details of data frames and lists, whereas section 4.3 is, in my opinion, a little on the tangiential side. if you're reading along about xtabs(), split(), and stack(), and you're zoning out, don't worry too much. you can come back to these things when you find a problem that necessitate them.

lattice graphics (section 4.4) are pretty cool when your data are appropriate to be shown in this fashion, so this section is worth a read, whereas, possibly with the exception of 'factors', most of section 4.5 can be safely skimmed or skipped at this point (as JV himself indicates).