Just playing with matrices in R. :-)
Not that it's difficult or anything, just wanted to practice coding in R.
And the code can be made quite compact and readable at the same time:
calculate.neighbors <- function(board)
{
shifted.up <- shift.up(board)
shifted.down <- shift.down(board)
neighbors <-
shift.left(shifted.up) + shifted.up + shift.right(shifted.up) +
shift.left(board) + shift.right(board) +
shift.left(shifted.down) + shifted.down + shift.right(shifted.down)
}
calculate.generation <- function(board)
{
neighbors <- calculate.neighbors(board)
remaining <- neighbors == 2
creating <- neighbors == 3
(board * remaining) + creating
}
In the code above, board is an R matrix, with values equal to 0 (empty cell) and 1 (occupied cell).
I especially like the last expression that returns the next generation... :-)
(Remember that * in R is matrix multiplication element by element, not the linear algebra matrix multiplication.
That combined with R's handling of TRUE/FALSE values (1 and 0 respectively) allows for the final expression to work as expected.)
The above assumes that you have the shift.up/down/left/right functions defined for matrices;
for instance, the matrixcalc package gives you that.
I preferred to code simplified versions of those functions myself - again, mainly as an exercise
(and thanks to that Life calculations are about 7% quicker, too).
Anyway, if you want to view or play with the source code, it's available on GitHub.
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