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katrinleinweber's solution

to Scrabble Score in the R Track

Published at Jul 13 2018 · 1 comment
Instructions
Test suite
Solution

Given a word, compute the scrabble score for that word.

Letter Values

You'll need these:

Letter                           Value
A, E, I, O, U, L, N, R, S, T       1
D, G                               2
B, C, M, P                         3
F, H, V, W, Y                      4
K                                  5
J, X                               8
Q, Z                               10

Examples

"cabbage" should be scored as worth 14 points:

  • 3 points for C
  • 1 point for A, twice
  • 3 points for B, twice
  • 2 points for G
  • 1 point for E

And to total:

  • 3 + 2*1 + 2*3 + 2 + 1
  • = 3 + 2 + 6 + 3
  • = 5 + 9
  • = 14

Extensions

  • You can play a double or a triple letter.
  • You can play a double or a triple word.

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

Inspired by the Extreme Startup game https://github.com/rchatley/extreme_startup

Submitting Incomplete Solutions

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

test_scrabble-score.R

source("./scrabble-score.R")
library(testthat)

context("scrabble score")

test_that("lowercase letter", {
  input <- "a"
  expect_equal(scrabble_score(input), 1)
})

test_that("uppercase letter", {
  input <- "A"
  expect_equal(scrabble_score(input), 1)
})

test_that("valuable letter", {
  input <- "f"
  expect_equal(scrabble_score(input), 4)
})

test_that("short word", {
  input <- "at"
  expect_equal(scrabble_score(input), 2)
})

test_that("short, valuable word", {
  input <- "zoo"
  expect_equal(scrabble_score(input), 12)
})

test_that("medium word", {
  input <- "street"
  expect_equal(scrabble_score(input), 6)
})

test_that("medium, valuable word", {
  input <- "quirky"
  expect_equal(scrabble_score(input), 22)
})

test_that("long, mixed-case word", {
  input <- "OxyphenButazone"
  expect_equal(scrabble_score(input), 41)
})

test_that("english-like word", {
  input <- "pinata"
  expect_equal(scrabble_score(input), 8)
})

test_that("empty input", {
  input <- ""
  expect_equal(scrabble_score(input), 0)
})

test_that("entire alphabet available", {
  input <- "abcdefghijklmnopqrstuvwxyz"
  expect_equal(scrabble_score(input), 87)
})

message("All tests passed for exercise: scrabble-score")
library(magrittr)

scrabble_score <- function(input){
  
  # match of letter to score
  score <- function(letter) {
    dplyr::case_when(
      letter %in% c("A", "E", "I", "O", "U", "L", "N", "R", "S", "T") ~ 1,
      letter %in% c("D", "G") ~ 2,
      letter %in% c("B", "C", "M", "P") ~ 3,
      letter %in% c("F", "H", "V", "W", "Y") ~ 4,
      letter %in% c("K") ~ 5,
      letter %in% c("J", "X") ~ 8,
      letter %in% c("Q", "Z") ~ 10
    )}
  
  # split input into letters
  # sum scores ups
  input %>% 
    toupper() %>% 
    strsplit("") %>% 
    purrr::map(.f = score) %>% 
    unlist() %>% 
    sum()
}

Community comments

Find this solution interesting? Ask the author a question to learn more.
Avatar of rawdamedia

Must look into 'purrr', as I prefer functional languages... :-D

What can you learn from this solution?

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