英文:
Append slice to slice of slices
问题
我有一个数据结构：
type PosList []int
type InvertedIndex struct {
Capacity int
Len int
IndexList []PosList
}
我在Add方法上遇到了问题：
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.Len == ii.Capacity {
newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
for i := 0; i < ii.Len; i++ {
newIndexList[i] = make([]int, len(ii.IndexList[i]))
copy(newIndexList[i], ii.IndexList[i])
}
ii.IndexList = newIndexList
}
ii.IndexList = ii.IndexList[0 : ii.Len+2]
ii.IndexList[docId] = posList
return
}
或者，我尝试了这样的方法：
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.Len == ii.Capacity {
newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
copy(newIndexList, ii.IndexList)
ii.IndexList = newIndexList
}
ii.IndexList = ii.IndexList[0 : ii.Len+2]
ii.IndexList[docId] = posList
return
}
这两种方法都不起作用，也许有人可以解释一下如何将一个切片追加到这样的结构中。
英文:
I have data structure:
type PosList []int
type InvertedIndex struct {
Capacity int
Len int
IndexList []PosList
}
I have problem with Add method:
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.Len == ii.Capacity {
newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
for i := 0; i < ii.Len; i++ {
newIndexList[i] = make([]int, len(ii.IndexList[i]))
copy(newIndexList[i], ii.IndexList[i])
}
ii.IndexList = newIndexList
}
ii.IndexList = ii.IndexList[0 : ii.Len+2]
ii.IndexList[docId] = posList
return
}
Or, i try something like this:
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.Len == ii.Capacity {
newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
copy(newIndexList, ii.IndexList)
ii.IndexList = newIndexList
}
ii.IndexList = ii.IndexList[0 : ii.Len+2]
ii.IndexList[docId] = posList
return
}
Both of them don't work, may be someone can explain how can i append a slice to structure like this.
答案1
得分: 0
我不确定我完全理解你在做什么，但是像这样的代码应该可以正常工作，将 slice 替换为 map：
type PosList []int
type InvertedIndex struct {
Len int
IndexList map[int]PosList
}
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.IndexList == nil {
ii.IndexList = make(map[int]PosList)
}
if _, ok := ii.IndexList[docId]; ok {
ii.IndexList[docId] = append(ii.IndexList[docId], posList...)
} else {
ii.IndexList[docId] = posList
}
ii.Len = len(ii.IndexList)
}
这段代码将 PosList 类型定义为一个整数切片，InvertedIndex 结构体包含一个整数 Len 和一个映射 IndexList，映射的键是整数，值是 PosList 类型。Add 方法用于向 IndexList 中添加位置列表 posList，并关联到文档 ID docId。如果 IndexList 为空，则先创建一个空的映射。如果 docId 已存在于 IndexList 中，则将 posList 追加到对应的位置列表中，否则直接将 posList 赋值给对应的位置列表。最后，更新 Len 的值为 IndexList 的长度。
英文:
I'm not sure I fully understand what you're doing, however something like this should just work fine, replacing the slice with a map :
type PosList []int
type InvertedIndex struct {
Len int
IndexList map[int]PosList
}
func (ii *InvertedIndex) Add(posList PosList, docId int) {
if ii.IndexList == nil {
ii.IndexList = make(map[int]PosList)
}
if _, ok := ii.IndexList[docId]; ok {
ii.IndexList[docId] = append(ii.IndexList[docId], posList...)
} else {
ii.IndexList[docId] = posList
}
ii.Len = len(ii.IndexList)
}
答案2
得分: 0
你的问题有些混乱。我猜你想创建一个典型的倒排索引。在这种情况下，你可能想要像这样做：
package main
import "fmt"
type DocId int
type Positions []int
type docIndex struct {
docId DocId
positions Positions
}
type InvertedIndex struct {
docIndexes []docIndex
}
func New() *InvertedIndex {
return &InvertedIndex{}
}
func (ii *InvertedIndex) Add(docId DocId, positions Positions) {
for i, di := range (*ii).docIndexes {
if di.docId == docId {
di.positions = append(di.positions, positions...)
(*ii).docIndexes[i] = di
return
}
}
di := docIndex{
docId: docId,
positions: positions,
}
(*ii).docIndexes = append((*ii).docIndexes, di)
}
func main() {
ii := New()
docId := DocId(11)
positions := Positions{42, 7}
ii.Add(docId, positions)
positions = Positions{21, 4}
ii.Add(docId, positions)
docId = DocId(22)
positions = Positions{84, 14}
ii.Add(docId, positions)
fmt.Printf("%+v\n", *ii)
}
输出结果为：
{docIndexes:[{docId:11 positions:[42 7 21 4]} {docId:22 positions:[84 14]}]}
语句：
di.positions = append(di.positions, positions...)
将一个切片追加到另一个切片中。
参考资料：
Appending to and copying slices
Arrays, slices (and strings): The mechanics of 'append'
英文:
You question is confusing. I assume that you are trying to create a typical inverted index. In which case, you probably want to do something like this:
package main
import "fmt"
type DocId int
type Positions []int
type docIndex struct {
docId DocId
positions Positions
}
type InvertedIndex struct {
docIndexes []docIndex
}
func New() *InvertedIndex {
return &InvertedIndex{}
}
func (ii *InvertedIndex) Add(docId DocId, positions Positions) {
for i, di := range (*ii).docIndexes {
if di.docId == docId {
di.positions = append(di.positions, positions...)
(*ii).docIndexes[i] = di
return
}
}
di := docIndex{
docId: docId,
positions: positions,
}
(*ii).docIndexes = append((*ii).docIndexes, di)
}
func main() {
ii := New()
docId := DocId(11)
positions := Positions{42, 7}
ii.Add(docId, positions)
positions = Positions{21, 4}
ii.Add(docId, positions)
docId = DocId(22)
positions = Positions{84, 14}
ii.Add(docId, positions)
fmt.Printf("%+v\n", *ii)
}
Output:
{docIndexes:[{docId:11 positions:[42 7 21 4]} {docId:22 positions:[84 14]}]}
The statement:
di.positions = append(di.positions, positions...)
appends a slice to a slice.
References:
Appending to and copying slices
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