为什么打印时Go的地图迭代顺序会有所不同？

Question

package main

import "fmt"

func main(){
    sample := map[string]string{
    "key1":"value1",
    "key2":"value2",
    "key3":"value3",
    }
    for i := 0;i<3;i++{
        fmt.Println(sample)
    }
}

The above go code just print a map[string]string three times.

I expect it to a fixed output,but it shows as the following:

map[key3:value3 key2:value2 key1:value1]
map[key1:value1 key3:value3 key2:value2]
map[key2:value2 key1:value1 key3:value3]

It varies!

while in python:

#!/bin/env python
#encoding=utf8

sample = {
    "key1":"value1",
    "key2":"value2",
    "key3":"value3",
}
for i in range(3):
    print sample

OutPut:

{'key3': 'value3', 'key2': 'value2', 'key1': 'value1'}
{'key3': 'value3', 'key2': 'value2', 'key1': 'value1'}
{'key3': 'value3', 'key2': 'value2', 'key1': 'value1'}`

Answer 1

You cannot rely on the order in which you will get the keys. The language spec says "A map is an unordered group of elements", and later "The iteration order over maps is not specified and is not guaranteed to be the same from one iteration to the next."