This is a special R script which can be used to generate a report. You can write normal text in roxygen comments.

First we set up some options (you do not have to do this):

The report begins here.

# boring examples as usual
set.seed(123)
x = rnorm(5)
mean(x)

## [1] 0.1935703

You can use the special syntax {{code}} to embed inline expressions, e.g. 2.1935703 is the mean of x plus 2. The code itself may contain braces, but these are not checked. Thus, perfectly valid (though very strange) R code such as {{2 + 3}} - {{4 - 5}} can lead to errors because 2 + 3}} - {{4 - 5 will be treated as inline code.

Now we continue writing the report. We can draw plots as well.

par(mar = c(4, 4, 0.1, 0.1))
plot(x)

Actually you do not have to write chunk options, in which case knitr will use default options. For example, the code below has no options attached:

var(x)

## [1] 0.6577564

quantile(x)

##          0%         25%         50%         75%        100% 
## -0.56047565 -0.23017749  0.07050839  0.12928774  1.55870831

And you can also write two chunks successively like this:

sum(x^2)  # chi-square distribution with df 5

## [1] 2.818373

sum((x - mean(x))^2)  # df is 4 now

## [1] 2.631026

Done. Call spin('knitr-spin.R') to make silk from sow's ear now and knit a lovely purse.