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katrinleinweber's solution

to Raindrops in the R Track

Published at Jul 13 2018 · 0 comments
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.

Examples

  • 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".

Installation

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

How to implement your solution

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.

How to run tests

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.

Source

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

Submitting Incomplete Solutions

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

test_raindrops.R

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 = "")
}

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