


Efficient Grouping and Summing of Struct Slices in Golang
In Golang, handling data efficiently is crucial. When dealing with slices of structs, tasks such as grouping and summing can become challenging. This guide addresses an efficient approach to group and sum a slice of structs based on specific fields.
Problem Statement
Consider the following struct:
type Register struct { id1 int id2 int id3 int id4 int id5 int id6 int id7 int id8 int money int }
The goal is to group registers by the fields id1, id2, id3, id4, id5, id6, id7, and id8 and then sum the associated money field.
Solution
The provided solution involves slight refactoring of the struct types. By extracting the key fields into a separate struct, Key, we can utilize the comparability of structs in Golang.
Refactored Types
type Key struct { id1 int id2 int id3 int id4 int id5 int id6 int id7 int id8 int } type Register struct { key Key money int }
Grouping and Summing
To achieve grouping and summing, we create a map[Key]int. The Key of the map represents the combination of id fields, while the value represents the sum of money for registers with the same key.
regs := []*Register{ {Key{id1: 345}, 1500}, {Key{id1: 345, id2: 140}, 2700}, {Key{id1: 345, id2: 140}, 1300}, {Key{id1: 345}, 1000}, {Key{id3: 999}, 1000}, {Key{id3: 999}, 2000}, } // calculate sum: m := map[Key]int{} for _, v := range regs { m[v.key] += v.money }
Output
The map provides a grouped and summed representation of the registers.
map[{345 0 0 0 0 0 0 0}:2500 {345 140 0 0 0 0 0 0}:4000 {0 0 999 0 0 0 0 0}:3000]
Enhanced Output
For improved readability, we can format the output as follows:
fmt.Println("Nice output:") for k, v := range m { fmt.Printf("%+3v: %d\n", k, v) }
Result
Nice output: {id1:345 id2: 0 id3: 0 id4: 0 id5: 0 id6: 0 id7: 0 id8: 0}: 2500 {id1:345 id2:140 id3: 0 id4: 0 id5: 0 id6: 0 id7: 0 id8: 0}: 4000 {id1: 0 id2: 0 id3:999 id4: 0 id5: 0 id6: 0 id7: 0 id8: 0}: 3000
Advantages
This approach offers several advantages:
- Simplified grouping and summing using maps
- Efficient handling of data by leveraging comparable structs
- Flexibility in handling different grouping criteria through the use of the Key struct
The above is the detailed content of How can I efficiently group and sum a slice of structs based on specific fields in Golang?. For more information, please follow other related articles on the PHP Chinese website!

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