Documentation
¶
Overview ¶
Package maps defines various functions useful with maps of any type.
This package does not have any special handling for non-reflexive keys (keys k where k != k), such as floating-point NaNs.
Index ¶
- func All[Map ~map[K]V, K comparable, V any](m Map) iter.Seq2[K, V]
- func Clone[M ~map[K]V, K comparable, V any](m M) M
- func Collect[K comparable, V any](seq iter.Seq2[K, V]) map[K]V
- func Copy[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2)
- func DeleteFunc[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool)
- func Equal[M1, M2 ~map[K]V, K, V comparable](m1 M1, m2 M2) bool
- func EqualFunc[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M2, eq func(V1, V2) bool) bool
- func Insert[Map ~map[K]V, K comparable, V any](m Map, seq iter.Seq2[K, V])
- func Keys[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[K]
- func Values[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[V]
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func All ¶ added in go1.23.0
func All[Map ~map[K]V, K comparable, V any](m Map) iter.Seq2[K, V]
All returns an iterator over key-value pairs from m. The iteration order is not specified and is not guaranteed to be the same from one call to the next.
Example ¶
package main
import (
"fmt"
"maps"
)
func main() {
m1 := map[string]int{
"one": 1,
"two": 2,
}
m2 := map[string]int{
"one": 10,
}
maps.Insert(m2, maps.All(m1))
fmt.Println("m2 is:", m2)
}
Output: m2 is: map[one:1 two:2]
func Clone ¶
func Clone[M ~map[K]V, K comparable, V any](m M) M
Clone returns a copy of m. This is a shallow clone: the new keys and values are set using ordinary assignment.
Example ¶
package main
import (
"fmt"
"maps"
)
func main() {
m1 := map[string]int{
"key": 1,
}
m2 := maps.Clone(m1)
m2["key"] = 100
fmt.Println(m1["key"])
fmt.Println(m2["key"])
m3 := map[string][]int{
"key": {1, 2, 3},
}
m4 := maps.Clone(m3)
fmt.Println(m4["key"][0])
m4["key"][0] = 100
fmt.Println(m3["key"][0])
fmt.Println(m4["key"][0])
}
Output: 1 100 1 100 100
func Collect ¶ added in go1.23.0
func Collect[K comparable, V any](seq iter.Seq2[K, V]) map[K]V
Collect collects key-value pairs from seq into a new map and returns it.
Example ¶
package main
import (
"fmt"
"maps"
"slices"
)
func main() {
s1 := []string{"zero", "one", "two", "three"}
m1 := maps.Collect(slices.All(s1))
fmt.Println("m1 is:", m1)
}
Output: m1 is: map[0:zero 1:one 2:two 3:three]
func Copy ¶
func Copy[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2)
Copy copies all key/value pairs in src adding them to dst. When a key in src is already present in dst, the value in dst will be overwritten by the value associated with the key in src.
Example ¶
package main
import (
"fmt"
"maps"
)
func main() {
m1 := map[string]int{
"one": 1,
"two": 2,
}
m2 := map[string]int{
"one": 10,
}
maps.Copy(m2, m1)
fmt.Println("m2 is:", m2)
m2["one"] = 100
fmt.Println("m1 is:", m1)
fmt.Println("m2 is:", m2)
m3 := map[string][]int{
"one": {1, 2, 3},
"two": {4, 5, 6},
}
m4 := map[string][]int{
"one": {7, 8, 9},
}
maps.Copy(m4, m3)
fmt.Println("m4 is:", m4)
m4["one"][0] = 100
fmt.Println("m3 is:", m3)
fmt.Println("m4 is:", m4)
}
Output: m2 is: map[one:1 two:2] m1 is: map[one:1 two:2] m2 is: map[one:100 two:2] m4 is: map[one:[1 2 3] two:[4 5 6]] m3 is: map[one:[100 2 3] two:[4 5 6]] m4 is: map[one:[100 2 3] two:[4 5 6]]
func DeleteFunc ¶
func DeleteFunc[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool)
DeleteFunc deletes any key/value pairs from m for which del returns true.
Example ¶
package main
import (
"fmt"
"maps"
)
func main() {
m := map[string]int{
"one": 1,
"two": 2,
"three": 3,
"four": 4,
}
maps.DeleteFunc(m, func(k string, v int) bool {
return v%2 != 0 // delete odd values
})
fmt.Println(m)
}
Output: map[four:4 two:2]
func Equal ¶
func Equal[M1, M2 ~map[K]V, K, V comparable](m1 M1, m2 M2) bool
Equal reports whether two maps contain the same key/value pairs. Values are compared using ==.
Example ¶
package main
import (
"fmt"
"maps"
)
func main() {
m1 := map[int]string{
1: "one",
10: "Ten",
1000: "THOUSAND",
}
m2 := map[int]string{
1: "one",
10: "Ten",
1000: "THOUSAND",
}
m3 := map[int]string{
1: "one",
10: "ten",
1000: "thousand",
}
fmt.Println(maps.Equal(m1, m2))
fmt.Println(maps.Equal(m1, m3))
}
Output: true false
func EqualFunc ¶
func EqualFunc[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M2, eq func(V1, V2) bool) bool
EqualFunc is like Equal, but compares values using eq. Keys are still compared with ==.
Example ¶
package main
import (
"fmt"
"maps"
"strings"
)
func main() {
m1 := map[int]string{
1: "one",
10: "Ten",
1000: "THOUSAND",
}
m2 := map[int][]byte{
1: []byte("One"),
10: []byte("Ten"),
1000: []byte("Thousand"),
}
eq := maps.EqualFunc(m1, m2, func(v1 string, v2 []byte) bool {
return strings.ToLower(v1) == strings.ToLower(string(v2))
})
fmt.Println(eq)
}
Output: true
func Insert ¶ added in go1.23.0
func Insert[Map ~map[K]V, K comparable, V any](m Map, seq iter.Seq2[K, V])
Insert adds the key-value pairs from seq to m. If a key in seq already exists in m, its value will be overwritten.
Example ¶
package main
import (
"fmt"
"maps"
"slices"
)
func main() {
m1 := map[int]string{
1000: "THOUSAND",
}
s1 := []string{"zero", "one", "two", "three"}
maps.Insert(m1, slices.All(s1))
fmt.Println("m1 is:", m1)
}
Output: m1 is: map[0:zero 1:one 2:two 3:three 1000:THOUSAND]
func Keys ¶ added in go1.23.0
func Keys[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[K]
Keys returns an iterator over keys in m. The iteration order is not specified and is not guaranteed to be the same from one call to the next.
Example ¶
package main
import (
"fmt"
"maps"
"slices"
)
func main() {
m1 := map[int]string{
1: "one",
10: "Ten",
1000: "THOUSAND",
}
keys := slices.Sorted(maps.Keys(m1))
fmt.Println(keys)
}
Output: [1 10 1000]
func Values ¶ added in go1.23.0
func Values[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[V]
Values returns an iterator over values in m. The iteration order is not specified and is not guaranteed to be the same from one call to the next.
Example ¶
package main
import (
"fmt"
"maps"
"slices"
)
func main() {
m1 := map[int]string{
1: "one",
10: "Ten",
1000: "THOUSAND",
}
values := slices.Sorted(maps.Values(m1))
fmt.Println(values)
}
Output: [THOUSAND Ten one]
Types ¶
This section is empty.
Source Files