djmurphy420/ggplot2-transition-guide — comment on commit ae050eb3133ce559adc1488edb96231fb2b08081
File: ggplot2-0.9.0-BW.Rnw line 1353
By yihui:

You can play with the feature of conditional evaluation to put two chunks in the same document, but evaluate one this time, and another next time, e.g.

```r
<<>>=
bw_version = TRUE # change it to FALSE for colored version
@
```r
<>=
qplot(...) + scale_gray()
@
<>=
qplot(...)
@
```

It is unbelievable that experts like Hadley and Baptiste do not use `\tableofcontents` and they prefer hand-made table of contents! No, no, no...