在Golang中按子数组值分组切片

问题描述：

I have an array of subarrays in the following format

And I would like to group it into a new slice based on the unit_type_name field in each subarray.

How can I group the slice by unit_type_name? Is there any native GO functions are available to do this? if I for loop the above then I will get a duplicate one, how can I avoid that?

答

I do not think golang has build-in functionality to help you do that (I may be wrong). My Assuption is that the php array will be converted to a json object. I managed to get the code below to help you sort your array (In JSON format) a based on the unit_type_name I created two structs which have json values similar to what the array keys would be

//StandardType ...
type StandardType struct {
    UnitID                int    `json:"unit_id"`
    IsFormal              int    `json:"is_formal"`
    AssignmentName        string `json:"assignment_name"`
    AssignmentDescription string `json:"assignment_description"`
    StandardID            int    `json:"standard_id"`
    StandardName          string `json:"standard_name"`
    StandardDescription   string `json:"standard_description"`
}

//AutoGenerated ...
type AutoGenerated struct {
    UnitID                int            `json:"unit_id"`
    AssignmentName        string         `json:"assignment_name"`
    AssignmentDescription string         `json:"assignment_description"`
    AssignmentTotalScore  int            `json:"assignment_total_score"`
    UnitTypeName          string         `json:"unit_type_name"`
    IsGraded              int            `json:"is_graded"`
    StandardID            int            `json:"standard_id"`
    ScoringType           string         `json:"scoring_type"`
    AttemptScore          int            `json:"attempt_score"`
    UnitDuedate           string         `json:"unit_duedate"`
    Standard              []StandardType `json:"standard"`
}
var jsonData = ``
func main() { 
    m := []AutoGenerated{}
    err := json.Unmarshal([]byte(jsonData), &m)
    if err != nil {
        panic(err)
    }

I created a map to hold the unit_type_name keys

    sliceKeys := make(map[string]string)

I created also map to hold the arrays that have similar unit_type_name keys in an AutoGenerated array

    groupedSlices := make(map[string][]AutoGenerated)

Then I loop through the decoded json string searching for the unit_type_name

    for i := range m {

If a unit_type_name already exists in the key slice I add the array item to the group slice

      if _, ok := sliceKeys[m[i].UnitTypeName]; ok {
        autogenerated := groupedSlices[m[i].UnitTypeName]
        autogenerated = append(autogenerated, m[i])
        groupedSlices[m[i].UnitTypeName] = autogenerated
      } else {

Else I create a new array key and add the item to it

        sliceKeys[m[i].UnitTypeName] = m[i].UnitTypeName
        autogenerated := []AutoGenerated{}
        autogenerated = append(autogenerated, m[i])
        groupedSlices[m[i].UnitTypeName] = autogenerated
     }
  }
  fmt.Println(sliceKeys)
  fmt.Println(groupedSlices)
}

input:

[{"unit_id": 6504,"assignment_name": "Grade assignment","assignment_description": "","assignment_total_score": 10,"unit_type_name": "Homework","is_graded": 1,"standard_id": 1219,
"scoring_type": "score","attempt_score": 8,"unit_duedate": "2016-02-10 09:00:00",
"standard": [{"unit_id": 6504,"is_formal": 1,"assignment_name": "Grade assignment","assignment_description": "",
"standard_id": 1220,"standard_name": "9-10.RL.3","standard_description": "Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a "
}]},{"unit_id": 6504,"assignment_name": "Grade assignment","assignment_description": "","assignment_total_score": 10,
"unit_type_name": "Paper","is_graded": 1,"standard_id": 1219,"scoring_type": "score","attempt_score": 8,"unit_duedate": "2016-02-10 09:00:00","standard": [{"unit_id": 6504,"is_formal": 1,"assignment_name": "Grade assignment","assignment_description": "","standard_id": 1220,"standard_name": "9-10.RL.3","standard_description": "Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a "}]},{
"unit_id": 6504,"assignment_name": "Grade assignment","assignment_description": "",
"assignment_total_score": 10,"unit_type_name": "Aything else","is_graded": 1,"standard_id": 1219,
"scoring_type": "score","attempt_score": 8,"unit_duedate": "2016-02-10 09:00:00","standard": [{
"unit_id": 6504,"is_formal": 1,"assignment_name": "Grade assignment","assignment_description": "","standard_id": 1220,
"standard_name": "9-10.RL.3","standard_description": "Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a "}]}]

output:

map[Homework:Homework Paper:Paper Aything else:Aything else]

map[
Homework:[
{6504 Grade assignment  10 Homework 1 1219 score 8 2016-02-10 09:00:00 [{6504 1 Grade assignment  1220 9-10.RL.3 Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a }]}
] 

Paper:[
{6504 Grade assignment  10 Paper 1 1219 score 8 2016-02-10 09:00:00 [{6504 1 Grade assignment  1220 9-10.RL.3 Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a }]}
] 

Aything else:[
{6504 Grade assignment  10 Aything else 1 1219 score 8 2016-02-10 09:00:00 [{6504 1 Grade assignment  1220 9-10.RL.3 Analyze how complex characters (e.g., those with multiple or conflicting motivations) develop over the course of a }]}]

]

在Golang中按子数组值分组切片

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