What's the recommended way of creating a pre-populated two-dimensional array in Scala? I've got the following code:
val map = for {
x <- (1 to size).toList
} yield for {
y <- (1 to size).toList
开发者_如何学编程} yield (x, y)
How do I make an array instead of list? Replacing .toList with .toArray doesn't compile. And is there a more concise or readable way of doing this than the nested for expressions?
On Scala 2.7, use Array.range
:
for {
x <- Array.range(1, 3)
} yield for {
y <- Array.range(1, 3)
} yield (x, y)
On Scala 2.8, use Array.tabulate
:
Array.tabulate(3,3)((x, y) => (x, y))
Among other ways, you can use use Array.range
and map
:
scala> Array.range(0,3).map(i => Array.range(0,3).map(j => (i,j)))
res0: Array[Array[(Int, Int)]] = Array(Array((0,0), (0,1), (0,2)), Array((1,0), (1,1), (1,2)), Array((2,0), (2,1), (2,2)))
Or you can use Array.fromFunction
:
scala> Array.fromFunction((i,j) => (i,j))(3,3)
res1: Array[Array[(Int, Int)]] = Array(Array((0,0), (0,1), (0,2)), Array((1,0), (1,1), (1,2)), Array((2,0), (2,1), (2,2)))
Scala 2.8 gives you even more options--look through the Array
object. (Actually, that's good advice for 2.7, also....)
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