英文:
Sort 2D array of structs Golang
问题
我想为一个二维结构体切片创建一个一致的排序，我是从一个映射中创建这个二维切片，所以顺序总是不同的。
我的结构体如下：
// Hit 包含了一个命中的数据。type Hit struct {Key string `json:"key"`Data []Field `json:"data"`}// Hits 存储了一系列的命中。type Hits [][]Hit
我想为Hits类型的内容提供一个一致的顺序。
我尝试过：
func (c Hits) Len() int { return len(c) }func (c Hits) Swap(i, j int) { c[i], c[j] = c[j], c[i] }func (c Hits) Less(i, j int) bool { return strings.Compare(c[i][0].Key, c[j][0].Key) == -1 }
但结果似乎仍然以随机顺序返回。
我在考虑可能对切片中的每个项进行哈希处理，但想知道是否有更简单的选项。
英文:
I want to create a consistent ordering for a 2D slice of structs, I am creating the 2D slice from a map so the order is always different.
My structs look like
// Hit contains the data for a hit.type Hit struct {Key string `json:"key"`Data []Field `json:"data"`}// Hits stores a list of hits.type Hits [][]Hit
I want to provide a consistent order for the contents of my Hits type.
I have tried:
func (c Hits) Len() int { return len(c) }func (c Hits) Swap(i, j int) { c[i], c[j] = c[j], c[i] }func (c Hits) Less(i, j int) bool { return strings.Compare(c[i][0].Key, c[j][0].Key) == -1 }
But the results still seem to come back in random order.
I was thinking of possibly hashing each item in the slice but thought there might be an easier option
答案1
得分: 1
map的迭代顺序是不确定的，因为它是一个哈希表（实际上并不是这样——将具有相同键的项按照相同的顺序插入到两个映射中，它们的迭代顺序将是相同的）。
假设你的映射是map[string]Hit，为了以确定的顺序迭代它，我会枚举映射中的键集，对其进行排序，然后使用排序后的集合来枚举映射。
类似这样的代码：
package mainimport ("fmt""sort")type Hit struct {Key string `json:"key"`Data []Field `json:"data"`}type Field struct {Value string `json:"value"`}func main() {var mapOfHits = getSomeHits()var sortedHits = sortHits(mapOfHits)for _, h := range sortedHits {fmt.Println(h.Key)}}func getSomeHits() map[string]Hit {return make(map[string]Hit, 0)}func sortHits(m map[string]Hit) []Hit {keys := make([]string, 0, len(m))sorted := make([]Hit, 0, len(m))for k := range m {keys = append(keys, k)}sort.Strings(keys)for _, k := range keys {sorted = append(sorted, m[k])}return sorted}
你可以点击这里查看示例代码。
英文:
The order of iteration over a map, because it's a hash table is rather indeterminate (it's not, really — insert items with the same keys in the same exact sequence into 2 maps and the order of iteration for each will be identical).
Assuming that your map is a map[string]Hit, to iterate it over in a determinate order, I would enumerate the set of keys in the map, sort that, and use that sorted set to enumerate the map.
package mainimport ("fmt""sort")type Hit struct {Key string `json:"key"`Data []Field `json:"data"`}type Field struct {Value string `json:"value"`}func main() {var mapOfHits = getSomeHits()var sortedHits = sortHits(mapOfHits)for _, h := range sortedHits {fmt.Println(h.Key)}}func getSomeHits() map[string]Hit {return make(map[string]Hit, 0)}func sortHits(m map[string]Hit) []Hit {keys := make([]string, 0, len(m))sorted := make([]Hit, 0, len(m))for k := range m {keys = append(keys, k)}sort.Strings(keys)for _, k := range keys {sorted = append(sorted, m[k])}return sorted}
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