Example 07: Functions and Iteration

── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
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── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
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✖ dplyr::lag()    masks stats::lag()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors
here() starts at /Users/kjhealy/Documents/courses/mptc

Trying Google Fonts...
Not found.

Trying Font Squirrel...
Not found.

Trying Font Library...
Not found.

Required font: `Myriad Pro SemiCondensed`, is not available on the system. Adding alias to `Helvetica Neue`

Trying Google Fonts...
Not found.

Trying Font Squirrel...
Not found.

Trying Font Library...
Not found.

Required font: `Myriad Pro Semibold SemiCondensed`, is not available on the system. Adding alias to `Helvetica Neue`

library(broom)

Functions

my_adder <- function(x, add = 1) {
  x + add
}

my_adder(10)

[1] 11

my_adder(1:10)

 [1]  2  3  4  5  6  7  8  9 10 11

# This won't work
# my_adder("a")

Guard clauses and error handling:

my_adder <- function(x, add = 1) {
  if(!is.numeric(x)) {
    return("Argument `x` must be numeric.")
  }

  x + add
}

my_adder("a")

[1] "Argument `x` must be numeric."

my_adder <- function(x, add = 1) {
  if(!is.numeric(x)) {
    return("Argument `x` must be numeric.")
  }

  if(!is.numeric(add)) {
    return("Argument `add` must be numeric.")
  }

  x + add
}

Here I use return() in the guard clauses in order to make this example work as part of the pipeline that creates the site. But really I should use stop().

my_adder(1:10, 5)

 [1]  6  7  8  9 10 11 12 13 14 15

my_adder(1:10, "c")

[1] "Argument `add` must be numeric."