将切片追加到切片的切片中。

huangapple
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英文:

Append slice to slice of slices

问题

我有一个数据结构：

  1. type PosList []int
  3. type InvertedIndex struct {
  4.   Capacity  int
  5.   Len       int
  6.   IndexList []PosList
  7. }

我在Add方法上遇到了问题：

  1. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  2.   if ii.Len == ii.Capacity {
  3.     newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
  4.     for i := 0; i < ii.Len; i++ {
  5.       newIndexList[i] = make([]int, len(ii.IndexList[i]))
  6.       copy(newIndexList[i], ii.IndexList[i])
  7.     }
  8.     ii.IndexList = newIndexList
  9.   }
  11.   ii.IndexList = ii.IndexList[0 : ii.Len+2]
  12.   ii.IndexList[docId] = posList
  13.   return
  14. }

或者，我尝试了这样的方法：

  1. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  3.   if ii.Len == ii.Capacity {
  4.     newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
  5.     copy(newIndexList, ii.IndexList)
  6.     ii.IndexList = newIndexList
  7.   }
  9.   ii.IndexList = ii.IndexList[0 : ii.Len+2]
  10.   ii.IndexList[docId] = posList
  11.   return
  12. }

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:

  1. type PosList []int
  3. type InvertedIndex struct {
  4.   Capacity  int
  5.   Len       int
  6.   IndexList []PosList
  7. }

I have problem with Add method:

  1. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  2.   if ii.Len == ii.Capacity {
  3.     newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
  4.     for i := 0; i &lt; ii.Len; i++ {
  5.       newIndexList[i] = make([]int, len(ii.IndexList[i]))
  6.       copy(newIndexList[i], ii.IndexList[i])
  7.     }
  8.     ii.IndexList = newIndexList
  9.   }
  11.   ii.IndexList = ii.IndexList[0 : ii.Len+2]
  12.   ii.IndexList[docId] = posList
  13.   return
  14. }

Or, i try something like this:

  1. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  3.   if ii.Len == ii.Capacity {
  4.     newIndexList := make([]PosList, ii.Len, (ii.Capacity+1)*2)
  5.     copy(newIndexList, ii.IndexList)
  6.     ii.IndexList = newIndexList
  7.   }
  9.   ii.IndexList = ii.IndexList[0 : ii.Len+2]
  10.   ii.IndexList[docId] = posList
  11.   return
  12. }

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：

  1. type PosList []int
  3. type InvertedIndex struct {
  4.     Len       int
  5.     IndexList map[int]PosList
  6. }
  8. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  9.     if ii.IndexList == nil {
  10.         ii.IndexList = make(map[int]PosList)
  11.     }
  12.     if _, ok := ii.IndexList[docId]; ok {
  13.         ii.IndexList[docId] = append(ii.IndexList[docId], posList...)
  14.     } else {
  15.         ii.IndexList[docId] = posList
  16.     }
  17.     
  18.     ii.Len = len(ii.IndexList)
  19. }

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 :

  1. type PosList []int
  3. type InvertedIndex struct {
  4. 	Len       int
  5. 	IndexList map[int]PosList
  6. }
  7. func (ii *InvertedIndex) Add(posList PosList, docId int) {
  8. 	if ii.IndexList == nil {
  9. 		ii.IndexList = make(map[int]PosList)
  10. 	}
  11. 	if _, ok := ii.IndexList[docId]; ok {
  12. 		ii.IndexList[docId] = append(ii.IndexList[docId], posList...)
  13. 	} else {
  14. 		ii.IndexList[docId] = posList
  15. 	}
  16. 	
  17. 	ii.Len = len(ii.IndexList)
  18. }

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：

  1. package main
  3. import "fmt"
  5. type DocId int
  7. type Positions []int
  9. type docIndex struct {
  10.     docId     DocId
  11.     positions Positions
  12. }
  14. type InvertedIndex struct {
  15.     docIndexes []docIndex
  16. }
  18. func New() *InvertedIndex {
  19.     return &InvertedIndex{}
  20. }
  22. func (ii *InvertedIndex) Add(docId DocId, positions Positions) {
  23.     for i, di := range (*ii).docIndexes {
  24.         if di.docId == docId {
  25.             di.positions = append(di.positions, positions...)
  26.             (*ii).docIndexes[i] = di
  27.             return
  28.         }
  29.     }
  30.     di := docIndex{
  31.         docId:     docId,
  32.         positions: positions,
  33.     }
  34.     (*ii).docIndexes = append((*ii).docIndexes, di)
  35. }
  37. func main() {
  38.     ii := New()
  39.     docId := DocId(11)
  40.     positions := Positions{42, 7}
  41.     ii.Add(docId, positions)
  42.     positions = Positions{21, 4}
  43.     ii.Add(docId, positions)
  44.     docId = DocId(22)
  45.     positions = Positions{84, 14}
  46.     ii.Add(docId, positions)
  47.     fmt.Printf("%+v\n", *ii)
  48. }

输出结果为：

  1. {docIndexes:[{docId:11 positions:[42 7 21 4]} {docId:22 positions:[84 14]}]}

语句：

  1. 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'

倒排索引

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:

  1. package main
  3. import &quot;fmt&quot;
  5. type DocId int
  7. type Positions []int
  9. type docIndex struct {
  10. 	docId     DocId
  11. 	positions Positions
  12. }
  14. type InvertedIndex struct {
  15. 	docIndexes []docIndex
  16. }
  18. func New() *InvertedIndex {
  19. 	return &amp;InvertedIndex{}
  20. }
  22. func (ii *InvertedIndex) Add(docId DocId, positions Positions) {
  23. 	for i, di := range (*ii).docIndexes {
  24. 		if di.docId == docId {
  25. 			di.positions = append(di.positions, positions...)
  26. 			(*ii).docIndexes[i] = di
  27. 			return
  28. 		}
  29. 	}
  30. 	di := docIndex{
  31. 		docId:     docId,
  32. 		positions: positions,
  33. 	}
  34. 	(*ii).docIndexes = append((*ii).docIndexes, di)
  35. }
  37. func main() {
  38. 	ii := New()
  39. 	docId := DocId(11)
  40. 	positions := Positions{42, 7}
  41. 	ii.Add(docId, positions)
  42. 	positions = Positions{21, 4}
  43. 	ii.Add(docId, positions)
  44. 	docId = DocId(22)
  45. 	positions = Positions{84, 14}
  46. 	ii.Add(docId, positions)
  47. 	fmt.Printf(&quot;%+v\n&quot;, *ii)
  48. }

Output:

  1. {docIndexes:[{docId:11 positions:[42 7 21 4]} {docId:22 positions:[84 14]}]}

The statement:

  1. di.positions = append(di.positions, positions...)

appends a slice to a slice.

References:

Appending to and copying slices

Arrays, slices (and strings): The mechanics of 'append'

inverted index

huangapple
  • 本文由 发表于 2014年3月29日 19:54:07
  • 转载请务必保留本文链接：https://go.coder-hub.com/22730754.html
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