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History of Idiom 27 > diff from v16 to v17

Edit summary for version 17 by :
[Go] Better playground code
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Version 16

2015-12-30, 17:26:25

Version 17

2015-12-30, 17:48:55

Idiom #27 Create a 3-dimensional array

Declare and initialize a 3D array x, having dimensions boundaries m, n, p, and containing real numbers.

Idiom #27 Create a 3-dimensional array

Declare and initialize a 3D array x, having dimensions boundaries m, n, p, and containing real numbers.

Code 
func make3D(m, n, p int) [][][]float64 {
	buf := make([]float64, m*n*p)

	x := make([][][]float64, m)
	for i := range x {
		x[i] = make([][]float64, n)
		for j := range x[i] {
			x[i][j] = buf[:p:p]
			buf = buf[p:]
		}
	}
	return x
}
Code 
func make3D(m, n, p int) [][][]float64 {
	buf := make([]float64, m*n*p)

	x := make([][][]float64, m)
	for i := range x {
		x[i] = make([][]float64, n)
		for j := range x[i] {
			x[i][j] = buf[:p:p]
			buf = buf[p:]
		}
	}
	return x
}
Comments bubble
This works even when m, n, p are not compile-time constants.
This code allocates one big slice for the numbers, then a few slices for intermediate dimensions.
To same function would be rewritten, for types other than float64.
Comments bubble
This works even when m, n, p are not compile-time constants.
This code allocates one big slice for the numbers, then a few slices for intermediate dimensions.
To same function would be rewritten, for types other than float64.
Doc URL
https://golang.org/doc/effective_go.html#two_dimensional_slices
Doc URL
https://golang.org/doc/effective_go.html#two_dimensional_slices
Demo URL
http://play.golang.org/p/SsCRecCclG
Demo URL
http://play.golang.org/p/AL5GBCgYTM