An answer of the exercise: Slices on a tour of Go

answer_pic.go

package main

import "code.google.com/p/go-tour/pic"

func Pic(dx, dy int) [][]uint8 {
	// Allocate two-dimensioanl array.
	a := make([][]uint8, dy)
	for i := 0; i < dy; i++ {
		a[i] = make([]uint8, dx)
	}
	
	// Do something.
	for i := 0; i < dy; i++ {
		for j := 0; j < dx; j++ {
			switch {
			case j % 15 == 0:
				a[i][j] = 240
			case j % 3 == 0:
				a[i][j] = 120
			case j % 5 == 0:
				a[i][j] = 150
			default:
				a[i][j] = 100
			}
		}
	}	
	return a
}

func main() {
	pic.Show(Pic)
}

package main

import (
	"golang.org/x/tour/pic"
)

func Pic(dx, dy int) [][]uint8 {
	result := make([][]uint8, dy)
	for y := range result {
		result[y] = make([]uint8, dx)
		for x := range result[y] {
			result[y][x] = uint8((x + y) / 2)
		}
	}
	return result
}

func main() {
	pic.Show(Pic)
}

package main

import (
	"math"

	"golang.org/x/tour/pic"
)

func Pic(dx, dy int) [][]uint8 {
	pic := make([][]uint8, dy, dy)

	for y := range pic {
		pic[y] = make([]uint8, dx)

		for x := range pic[y] {
			pic[y][x] = uint8(float64(x^y-y^x) / math.Pi)
		}
	}

	return pic
}

func main() {
	pic.Show(Pic)
}

package main

import (
	"math"

	"golang.org/x/tour/pic"
)

func Pic(dx, dy int) [][]uint8 {
	pic := make([][]uint8, dy, dy)
	i := 10
	for y := range pic {
		pic[y] = make([]uint8, dx)

		for x := range pic[y] {

			i++
			pic[y][x] = uint8(float64((x+y)*i) / math.Pi)
		}
	}

	return pic
}

func main() {
	pic.Show(Pic)
}