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Instructions

Test suite

Solution

Convert a number to a string, the contents of which depend on the number's factors.

- If the number has 3 as a factor, output 'Pling'.
- If the number has 5 as a factor, output 'Plang'.
- If the number has 7 as a factor, output 'Plong'.
- If the number does not have 3, 5, or 7 as a factor, just pass the number's digits straight through.

- 28's factors are 1, 2, 4,
**7**, 14, 28.- In raindrop-speak, this would be a simple "Plong".

- 30's factors are 1, 2,
**3**,**5**, 6, 10, 15, 30.- In raindrop-speak, this would be a "PlingPlang".

- 34 has four factors: 1, 2, 17, and 34.
- In raindrop-speak, this would be "34".

See this guide for instructions on how to setup your local R environment.

In each problem folder, there is a file named `<exercise_name>.R`

containing a function that returns a `NULL`

value. Place your implementation inside the body of the function.

Inside of RStudio, simply execute the `test_<exercise_name>.R`

script. This can be conveniently done with testthat's `auto_test`

function. Because exercism code and tests are in the same folder, use this same path for both `code_path`

and `test_path`

parameters. On the command-line, you can also run `Rscript test_<exercise_name>.R`

.

A variation on a famous interview question intended to weed out potential candidates. http://jumpstartlab.com

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
source("./raindrops.R")
library(testthat)
context("raindrops")
test_that("the sound for 1 is 1", {
number <- 1
expect_equal(raindrops(number), "1")
})
test_that("the sound for 3 is Pling", {
number <- 3
expect_equal(raindrops(number), "Pling")
})
test_that("the sound for 5 is Plang", {
number <- 5
expect_equal(raindrops(number), "Plang")
})
test_that("the sound for 7 is Plong", {
number <- 7
expect_equal(raindrops(number), "Plong")
})
test_that("the sound for 6 is Pling as it has a factor 3", {
number <- 6
expect_equal(raindrops(number), "Pling")
})
test_that("2 to the power 3 does not make a raindrop sound as 3 is the exponent
not the base", {
number <- 8
expect_equal(raindrops(number), "8")
})
test_that("the sound for 9 is Pling as it has a factor 3", {
number <- 9
expect_equal(raindrops(number), "Pling")
})
test_that("the sound for 10 is Plang as it has a factor 5", {
number <- 10
expect_equal(raindrops(number), "Plang")
})
test_that("the sound for 14 is Plong as it has a factor of 7", {
number <- 14
expect_equal(raindrops(number), "Plong")
})
test_that("the sound for 15 is PlingPlang as it has factors 3 and 5", {
number <- 15
expect_equal(raindrops(number), "PlingPlang")
})
test_that("the sound for 21 is PlingPlong as it has factors 3 and 7", {
number <- 21
expect_equal(raindrops(number), "PlingPlong")
})
test_that("the sound for 25 is Plang as it has a factor 5", {
number <- 25
expect_equal(raindrops(number), "Plang")
})
test_that("the sound for 27 is Pling as it has a factor 3", {
number <- 27
expect_equal(raindrops(number), "Pling")
})
test_that("the sound for 35 is PlangPlong as it has factors 5 and 7", {
number <- 35
expect_equal(raindrops(number), "PlangPlong")
})
test_that("the sound for 49 is Plong as it has a factor 7", {
number <- 49
expect_equal(raindrops(number), "Plong")
})
test_that("the sound for 52 is 52", {
number <- 52
expect_equal(raindrops(number), "52")
})
test_that("the sound for 105 is PlingPlangPlong as it has factors 3, 5 and 7", {
number <- 105
expect_equal(raindrops(number), "PlingPlangPlong")
})
test_that("the sound for 3125 is Plang as it has a factor 5", {
number <- 3125
expect_equal(raindrops(number), "Plang")
})
message("All tests passed for exercise: raindrops")
```

```
raindrops <- function(number) {
sound <- ""
if (number %% 3 == 0)
sound <- append(sound, 'Pling')
if (number %% 5 == 0)
sound <- append(sound, 'Plang')
if (number %% 7 == 0)
sound <- append(sound, 'Plong')
if (!(number %% 3 == 0 | number %% 5 == 0 | number %% 7 == 0))
return(as.character(number))
paste(sound, collapse = "")
}
```

A huge amount can be learned from reading other peopleâ€™s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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