CODEWITHSUNDEEP
r
lemmingxuan
lemmingxuan

Reputation: 709

what's the meaning of two parenthesis in R language

when I am learning the ggthemes package in R,Here's a link!.I see code as follow:

p + geom_rangeframe() +
    theme_tufte() +
    scale_x_continuous(breaks = extended_range_breaks()(mtcars$wt))

so I confuse what's the meaning of extended_range_breaks()(mtcars$wt)

extended_range_breaks is a function in ggthemes package.

function name follows a (),why there is the second () with parameter mtcars$wt in it?how the function extended_range_breaks accepts the parameter?

in a normal case,I can only understand usage like this:

extended_range_breaks(mtcars$wt)

Upvotes: 2

Views: 134

Answers (1)

akuiper
akuiper

Reputation: 214927

I guess what it means is that extended_range_breaks() returns another function. Here is a simplified example of returning function in R:

myFun <- function() { function(x) x }
myFun()
function(x) x
<environment: 0x10fad05b8>

myFun()(1)
[1] 1

You see that myFun() returns another function and you can call the function further by passing the parameter as myFun()(1).

Upvotes: 3

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