(This article was first published on

**The stupidest thing... » R**, and kindly contributed to R-bloggers)An R tip:

Did you know that `x[c(5,3)]`

is the same as `x[[5]][[3]]`

?

I should make more thorough use of this.

In the help file for `[[`

:

`[[`

can be applied recursively to lists, so that if the single index`i`

is a vector of length`p`

,`alist[[i]]`

is equivalent to`alist[[i1]]...[[ip]]`

providing all but the final indexing results in a list.

I never knew this; I came across it when playing around (i.e., not paying proper attention) in the back of the room at an R course.

Did you know that `[[`

had a help file? Type `?"[["`

To

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