# Some quibbles about “The R Book” by Michael Crawley

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A friend recently bought *The R Book* and I said I would tell him of problems that I’ve noticed with it. You can eavesdrop.

### Page 4

The word “library” is used instead of “package”. This (common) error substantially raises the blood pressure of some people — probably to an unwarranted extent.

An R *package *is a group of functions, data and their documentation. These are the things that are in *repositories *like CRAN (where there are over two thousand packages). A package is installed onto your machine into a *library*.

You are unlikely to call a book a library; don’t call a package a library.

Part of the problem is that packages are attached with the `library` function:

`> library(fortunes)`

That is why some instructions have you do the same thing via:

`> require(fortunes)`

Some of the people whose blood pressure is abnormally raised by seeing this mistake are very important to R, so please get this right.

### Page 11

An example value is:

`3.9+4.5i`

that is, a complex number. This is in the chapter called “Essentials of the R Language”. I’ve been using R and a language not unlike R for a quarter century. The only time I recall using complex numbers is when documenting them. Complex numbers don’t match my definition of “essential”.

There is a certain amount of irony for a 600-word blog post to take *n* lines to complain about a 900-page book wasting one line. However, the complex number is an extreme example of a common occurrence in the chapter. There is a lot of the chapter that I don’t find particularly essential.

My take on “essential” is Some hints for the R beginner.

### Page 16:

`A<-1:10`

`B<-c(2,4,8)`

These are two examples of a general feature: while the author’s keyboard seems to work perfectly fine for text, the space-bar is mysteriously broken for R code.

It is clearer to write these as:

`> A <- 1:10`

`> B <- c(2, 4, 8)`

The assignment arrow shows up as a separate entity. Spacesaidunderstanding.

### Page 21

The same thing, but this time it’s serious.

x<5

really, really should have spaces around the less-than operator.

There is no trouble with this particular example, but what if the example were with minus five?

`x<-5`

does not give you a logical vector with `TRUE` values when `x` is less than minus five. It changes `x` to have the single value 5.

This and a whole bunch of other R gotchas are in The R Inferno.

### Page 107

The values in the body of a matrix can only be numbers.

That is a false statement. In particular, if `x` is a numeric matrix, then the result of

`x < -5`

is a matrix of logical values (and is the same dimension as `x`).

### Pages 323-324

This be praise, not quibble.

The book uses “explanatory variables” and “response” in the statistical regression context. It doesn’t enter into the dependent-independent muddle.

## Other views

Amazon has several reviews of *The R Book*. There is a range of opinions from very positive to quite negative. A common complaint is that the material is disorganized.

## Questions

The points I have raised are from a quick glance through the book. Are there other things in the book that should be pointed out to help the unwary?

## Epilogue

I don’t think there is such a thing as the best book on R. There **can **be the best book on R for you as an individual. Which one is the best will depend on where you are and where you want to go. A partial list of your choices is Books related to R.

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