README.md

In alexpavlakis/sudoku: Simple Functions for Working with Sudoku Puzzles

sudokuplyr

The goal of sudokuplyr is to provide simple functions for solving, creating, and analyzing sudoku puzzles in R.

Installation

You can install sudokuplyr from github with:

# install.packages("devtools")
devtools::install_github("alexpavlakis/sudokuplyr")

Usage

The following methods are available for objects of class sudoku:

• print
• plot
• solve
• summary

as.sudoku will convert sudoku puzzles represented as matrices, vectors, or strings into objects of class sudoku.

# A sudoku in string format, with periods for unknown cells
raw_sudoku <- "1.......2.9.4...5...6...7...5.9.3.......7.......85..4.7.....6...3...9.8...2.....1"
s <- as.sudoku(raw_sudoku)

# Print
print(s)
#>                           
#>  + - - - + - - - + - - - +
#>  | 1     |       | 7     |
#>  |   9   | 5     |   3   |
#>  |     6 |       |     2 |
#>  + - - - + - - - + - - - +
#>  |   4   | 9   8 |       |
#>  |       |   7 5 |       |
#>  |       | 3     |   9   |
#>  + - - - + - - - + - - - +
#>  |     7 |       | 6     |
#>  |   5   |     4 |   8   |
#>  | 2     |       |     1 |
#>  + - - - + - - - + - - - +

# Solve
solve(s)
#>                           
#>  + - - - + - - - + - - - +
#>  | 1 2 5 | 4 9 3 | 7 6 8 |
#>  | 7 9 8 | 5 2 6 | 1 3 4 |
#>  | 4 3 6 | 1 8 7 | 9 5 2 |
#>  + - - - + - - - + - - - +
#>  | 3 4 1 | 9 6 8 | 5 2 7 |
#>  | 8 6 9 | 2 7 5 | 4 1 3 |
#>  | 5 7 2 | 3 4 1 | 8 9 6 |
#>  + - - - + - - - + - - - +
#>  | 9 1 7 | 8 3 2 | 6 4 5 |
#>  | 6 5 3 | 7 1 4 | 2 8 9 |
#>  | 2 8 4 | 6 5 9 | 3 7 1 |
#>  + - - - + - - - + - - - +

# Plot
plot(s)

# Summarize
summary(s)
#>                           
#>  + - - - + - - - + - - - +
#>  | 1     |       | 7     |
#>  |   9   | 5     |   3   |
#>  |     6 |       |     2 |
#>  + - - - + - - - + - - - +
#>  |   4   | 9   8 |       |
#>  |       |   7 5 |       |
#>  |       | 3     |   9   |
#>  + - - - + - - - + - - - +
#>  |     7 |       | 6     |
#>  |   5   |     4 |   8   |
#>  | 2     |       |     1 |
#>  + - - - + - - - + - - - +
#>  clues:           21 
#>  naked singles:   0 
#>  hidden singles:  0 
#>  legal solution:  TRUE 
#>  unique solution: TRUE

solve_sudoku, print_sudoku, analyze_sudoku, and plot_sudoku operate on 9x9 matrices directly.

solve_sudoku completes puzzles in the blink of an eye. The example below shows the time taken to solve an easy puzzle (49 empty cells) and a hard puzzle (59 empty cells) that come with sudokuplyr. Both are solved in a fraction of a millisecond on a MacBook Air.

library(microbenchmark)

m <- microbenchmark(easy = solve(sudoku),
                    hard = solve(hard_sudoku), times = 100, unit = 'ms')

print(m, digits = 2)
#> Unit: milliseconds
#>  expr  min   lq mean median   uq  max neval
#>  easy 0.34 0.36 0.39   0.39 0.40 0.55   100
#>  hard 0.60 0.63 0.69   0.65 0.67 1.31   100

generate_sudoku creates randomly generated complete sudoku puzzles. The seed argument can be used to create reproducible random puzzles or left NULL (default). generate_puzzle creates randomly generated incomplete sudoku puzzles with a specified number of clues.

new_puzzle <- generate_puzzle(clues = 32, unique = TRUE, seed = 56)
print(new_puzzle)
#>                           
#>  + - - - + - - - + - - - +
#>  | 4   6 | 7     | 3 9   |
#>  |       |       |   6 8 |
#>  | 5     |   9   |     7 |
#>  + - - - + - - - + - - - +
#>  | 3     |     6 | 9     |
#>  |     7 |   8   | 6     |
#>  |       | 5     |   8   |
#>  + - - - + - - - + - - - +
#>  | 8     | 2 3   | 1   9 |
#>  | 2 1   |     7 |   4   |
#>  |   7 4 |       | 2   3 |
#>  + - - - + - - - + - - - +

get_all_solutions generates all possible solutions for a given puzzle. Puzzles with fewer than 20-25 clues (depending on the puzzle, of course), can have a lot of solutions, and this function can take a while to find them all. Beware. Most puzzles that appear in newspapers and magazines have only one solution.

# This puzzle has a lot of solutions
puzzle <- generate_puzzle(clues = 28, unique = FALSE, seed = 56)
all_solutions <- get_all_solutions(puzzle, stop_early = FALSE)
length(all_solutions)
#> [1] 898

`

alexpavlakis/sudoku documentation built on Feb. 1, 2020, 6:49 p.m.