Documentation
¶
Overview ¶
Package slices defines various functions useful with slices of any type.
Index ¶
- func BinarySearch[S ~[]E, E cmp.Ordered](x S, target E) (int, bool)
- func BinarySearchFunc[S ~[]E, E, T any](x S, target T, cmp func(E, T) int) (int, bool)
- func Clip[S ~[]E, E any](s S) S
- func Clone[S ~[]E, E any](s S) S
- func Compact[S ~[]E, E comparable](s S) S
- func CompactFunc[S ~[]E, E any](s S, eq func(E, E) bool) S
- func Compare[S ~[]E, E cmp.Ordered](s1, s2 S) int
- func CompareFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, cmp func(E1, E2) int) int
- func Contains[S ~[]E, E comparable](s S, v E) bool
- func ContainsFunc[S ~[]E, E any](s S, f func(E) bool) bool
- func Delete[S ~[]E, E any](s S, i, j int) S
- func DeleteFunc[S ~[]E, E any](s S, del func(E) bool) S
- func Equal[S ~[]E, E comparable](s1, s2 S) bool
- func EqualFunc[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, eq func(E1, E2) bool) bool
- func Grow[S ~[]E, E any](s S, n int) S
- func Index[S ~[]E, E comparable](s S, v E) int
- func IndexFunc[S ~[]E, E any](s S, f func(E) bool) int
- func Insert[S ~[]E, E any](s S, i int, v ...E) S
- func IsSorted[S ~[]E, E cmp.Ordered](x S) bool
- func IsSortedFunc[S ~[]E, E any](x S, cmp func(a, b E) int) bool
- func Max[S ~[]E, E cmp.Ordered](x S) E
- func MaxFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E
- func Min[S ~[]E, E cmp.Ordered](x S) E
- func MinFunc[S ~[]E, E any](x S, cmp func(a, b E) int) E
- func Replace[S ~[]E, E any](s S, i, j int, v ...E) S
- func Reverse[S ~[]E, E any](s S)
- func Sort[S ~[]E, E cmp.Ordered](x S)
- func SortFunc[S ~[]E, E any](x S, cmp func(a, b E) int)
- func SortStableFunc[S ~[]E, E any](x S, cmp func(a, b E) int)
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func BinarySearch ¶
BinarySearch searches for target in a sorted slice and returns the position where target is found, or the position where target would appear in the sort order; it also returns a bool saying whether the target is really found in the slice. The slice must be sorted in increasing order.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
names := []string{"Alice", "Bob", "Vera"}
n, found := slices.BinarySearch(names, "Vera")
fmt.Println("Vera:", n, found)
n, found = slices.BinarySearch(names, "Bill")
fmt.Println("Bill:", n, found)
}
Output: Vera: 2 true Bill: 1 false
func BinarySearchFunc ¶
BinarySearchFunc works like BinarySearch, but uses a custom comparison function. The slice must be sorted in increasing order, where "increasing" is defined by cmp. cmp should return 0 if the slice element matches the target, a negative number if the slice element precedes the target, or a positive number if the slice element follows the target. cmp must implement the same ordering as the slice, such that if cmp(a, t) < 0 and cmp(b, t) >= 0, then a must precede b in the slice.
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
)
func main() {
type Person struct {
Name string
Age int
}
people := []Person{
{"Alice", 55},
{"Bob", 24},
{"Gopher", 13},
}
n, found := slices.BinarySearchFunc(people, Person{"Bob", 0}, func(a, b Person) int {
return cmp.Compare(a.Name, b.Name)
})
fmt.Println("Bob:", n, found)
}
Output: Bob: 1 true
func Clip ¶
func Clip[S ~[]E, E any](s S) S
Clip removes unused capacity from the slice, returning s[:len(s):len(s)].
func Clone ¶
func Clone[S ~[]E, E any](s S) S
Clone returns a copy of the slice. The elements are copied using assignment, so this is a shallow clone.
func Compact ¶
func Compact[S ~[]E, E comparable](s S) S
Compact replaces consecutive runs of equal elements with a single copy. This is like the uniq command found on Unix. Compact modifies the contents of the slice s and returns the modified slice, which may have a smaller length. When Compact discards m elements in total, it might not modify the elements s[len(s)-m:len(s)]. If those elements contain pointers you might consider zeroing those elements so that objects they reference can be garbage collected.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
seq := []int{0, 1, 1, 2, 3, 5, 8}
seq = slices.Compact(seq)
fmt.Println(seq)
}
Output: [0 1 2 3 5 8]
func CompactFunc ¶
CompactFunc is like Compact but uses an equality function to compare elements. For runs of elements that compare equal, CompactFunc keeps the first one.
Example ¶
package main
import (
"fmt"
"slices"
"strings"
)
func main() {
names := []string{"bob", "Bob", "alice", "Vera", "VERA"}
names = slices.CompactFunc(names, func(a, b string) bool {
return strings.ToLower(a) == strings.ToLower(b)
})
fmt.Println(names)
}
Output: [bob alice Vera]
func Compare ¶
Compare compares the elements of s1 and s2, using cmp.Compare on each pair of elements. The elements are compared sequentially, starting at index 0, until one element is not equal to the other. The result of comparing the first non-matching elements is returned. If both slices are equal until one of them ends, the shorter slice is considered less than the longer one. The result is 0 if s1 == s2, -1 if s1 < s2, and +1 if s1 > s2.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
names := []string{"Alice", "Bob", "Vera"}
fmt.Println("Equal:", slices.Compare(names, []string{"Alice", "Bob", "Vera"}))
fmt.Println("V < X:", slices.Compare(names, []string{"Alice", "Bob", "Xena"}))
fmt.Println("V > C:", slices.Compare(names, []string{"Alice", "Bob", "Cat"}))
fmt.Println("3 > 2:", slices.Compare(names, []string{"Alice", "Bob"}))
}
Output: Equal: 0 V < X: -1 V > C: 1 3 > 2: 1
func CompareFunc ¶
CompareFunc is like Compare but uses a custom comparison function on each pair of elements. The result is the first non-zero result of cmp; if cmp always returns 0 the result is 0 if len(s1) == len(s2), -1 if len(s1) < len(s2), and +1 if len(s1) > len(s2).
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
"strconv"
)
func main() {
numbers := []int{0, 43, 8}
strings := []string{"0", "0", "8"}
result := slices.CompareFunc(numbers, strings, func(n int, s string) int {
sn, err := strconv.Atoi(s)
if err != nil {
return 1
}
return cmp.Compare(n, sn)
})
fmt.Println(result)
}
Output: 1
func Contains ¶
func Contains[S ~[]E, E comparable](s S, v E) bool
Contains reports whether v is present in s.
func ContainsFunc ¶
ContainsFunc reports whether at least one element e of s satisfies f(e).
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, -10, 8}
hasNegative := slices.ContainsFunc(numbers, func(n int) bool {
return n < 0
})
fmt.Println("Has a negative:", hasNegative)
hasOdd := slices.ContainsFunc(numbers, func(n int) bool {
return n%2 != 0
})
fmt.Println("Has an odd number:", hasOdd)
}
Output: Has a negative: true Has an odd number: false
func Delete ¶
Delete removes the elements s[i:j] from s, returning the modified slice. Delete panics if s[i:j] is not a valid slice of s. Delete is O(len(s)-j), so if many items must be deleted, it is better to make a single call deleting them all together than to delete one at a time. Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those elements contain pointers you might consider zeroing those elements so that objects they reference can be garbage collected.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
letters := []string{"a", "b", "c", "d", "e"}
letters = slices.Delete(letters, 1, 4)
fmt.Println(letters)
}
Output: [a e]
func DeleteFunc ¶
DeleteFunc removes any elements from s for which del returns true, returning the modified slice. When DeleteFunc removes m elements, it might not modify the elements s[len(s)-m:len(s)]. If those elements contain pointers you might consider zeroing those elements so that objects they reference can be garbage collected.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
seq := []int{0, 1, 1, 2, 3, 5, 8}
seq = slices.DeleteFunc(seq, func(n int) bool {
return n%2 != 0 // delete the odd numbers
})
fmt.Println(seq)
}
Output: [0 2 8]
func Equal ¶
func Equal[S ~[]E, E comparable](s1, s2 S) bool
Equal reports whether two slices are equal: the same length and all elements equal. If the lengths are different, Equal returns false. Otherwise, the elements are compared in increasing index order, and the comparison stops at the first unequal pair. Floating point NaNs are not considered equal.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, 8}
fmt.Println(slices.Equal(numbers, []int{0, 42, 8}))
fmt.Println(slices.Equal(numbers, []int{10}))
}
Output: true false
func EqualFunc ¶
EqualFunc reports whether two slices are equal using an equality function on each pair of elements. If the lengths are different, EqualFunc returns false. Otherwise, the elements are compared in increasing index order, and the comparison stops at the first index for which eq returns false.
Example ¶
package main
import (
"fmt"
"slices"
"strconv"
)
func main() {
numbers := []int{0, 42, 8}
strings := []string{"000", "42", "0o10"}
equal := slices.EqualFunc(numbers, strings, func(n int, s string) bool {
sn, err := strconv.ParseInt(s, 0, 64)
if err != nil {
return false
}
return n == int(sn)
})
fmt.Println(equal)
}
Output: true
func Grow ¶
Grow increases the slice's capacity, if necessary, to guarantee space for another n elements. After Grow(n), at least n elements can be appended to the slice without another allocation. If n is negative or too large to allocate the memory, Grow panics.
func Index ¶
func Index[S ~[]E, E comparable](s S, v E) int
Index returns the index of the first occurrence of v in s, or -1 if not present.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, 8}
fmt.Println(slices.Index(numbers, 8))
fmt.Println(slices.Index(numbers, 7))
}
Output: 2 -1
func IndexFunc ¶
IndexFunc returns the first index i satisfying f(s[i]), or -1 if none do.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, -10, 8}
i := slices.IndexFunc(numbers, func(n int) bool {
return n < 0
})
fmt.Println("First negative at index", i)
}
Output: First negative at index 2
func Insert ¶
Insert inserts the values v... into s at index i, returning the modified slice. The elements at s[i:] are shifted up to make room. In the returned slice r, r[i] == v[0], and r[i+len(v)] == value originally at r[i]. Insert panics if i is out of range. This function is O(len(s) + len(v)).
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
names := []string{"Alice", "Bob", "Vera"}
names = slices.Insert(names, 1, "Bill", "Billie")
names = slices.Insert(names, len(names), "Zac")
fmt.Println(names)
}
Output: [Alice Bill Billie Bob Vera Zac]
func IsSorted ¶
IsSorted reports whether x is sorted in ascending order.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
fmt.Println(slices.IsSorted([]string{"Alice", "Bob", "Vera"}))
fmt.Println(slices.IsSorted([]int{0, 2, 1}))
}
Output: true false
func IsSortedFunc ¶
IsSortedFunc reports whether x is sorted in ascending order, with cmp as the comparison function as defined by SortFunc.
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
"strings"
)
func main() {
names := []string{"alice", "Bob", "VERA"}
isSortedInsensitive := slices.IsSortedFunc(names, func(a, b string) int {
return cmp.Compare(strings.ToLower(a), strings.ToLower(b))
})
fmt.Println(isSortedInsensitive)
fmt.Println(slices.IsSorted(names))
}
Output: true false
func Max ¶
Max returns the maximal value in x. It panics if x is empty. For floating-point E, Max propagates NaNs (any NaN value in x forces the output to be NaN).
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, -10, 8}
fmt.Println(slices.Max(numbers))
}
Output: 42
func MaxFunc ¶
MaxFunc returns the maximal value in x, using cmp to compare elements. It panics if x is empty. If there is more than one maximal element according to the cmp function, MaxFunc returns the first one.
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
)
func main() {
type Person struct {
Name string
Age int
}
people := []Person{
{"Gopher", 13},
{"Alice", 55},
{"Vera", 24},
{"Bob", 55},
}
firstOldest := slices.MaxFunc(people, func(a, b Person) int {
return cmp.Compare(a.Age, b.Age)
})
fmt.Println(firstOldest.Name)
}
Output: Alice
func Min ¶
Min returns the minimal value in x. It panics if x is empty. For floating-point numbers, Min propagates NaNs (any NaN value in x forces the output to be NaN).
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
numbers := []int{0, 42, -10, 8}
fmt.Println(slices.Min(numbers))
}
Output: -10
func MinFunc ¶
MinFunc returns the minimal value in x, using cmp to compare elements. It panics if x is empty. If there is more than one minimal element according to the cmp function, MinFunc returns the first one.
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
)
func main() {
type Person struct {
Name string
Age int
}
people := []Person{
{"Gopher", 13},
{"Bob", 5},
{"Vera", 24},
{"Bill", 5},
}
firstYoungest := slices.MinFunc(people, func(a, b Person) int {
return cmp.Compare(a.Age, b.Age)
})
fmt.Println(firstYoungest.Name)
}
Output: Bob
func Replace ¶
Replace replaces the elements s[i:j] by the given v, and returns the modified slice. Replace panics if s[i:j] is not a valid slice of s.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
names := []string{"Alice", "Bob", "Vera", "Zac"}
names = slices.Replace(names, 1, 3, "Bill", "Billie", "Cat")
fmt.Println(names)
}
Output: [Alice Bill Billie Cat Zac]
func Reverse ¶
func Reverse[S ~[]E, E any](s S)
Reverse reverses the elements of the slice in place.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
names := []string{"alice", "Bob", "VERA"}
slices.Reverse(names)
fmt.Println(names)
}
Output: [VERA Bob alice]
func Sort ¶
Sort sorts a slice of any ordered type in ascending order. When sorting floating-point numbers, NaNs are ordered before other values.
Example ¶
package main
import (
"fmt"
"slices"
)
func main() {
smallInts := []int8{0, 42, -10, 8}
slices.Sort(smallInts)
fmt.Println(smallInts)
}
Output: [-10 0 8 42]
func SortFunc ¶
SortFunc sorts the slice x in ascending order as determined by the cmp function. This sort is not guaranteed to be stable. cmp(a, b) should return a negative number when a < b, a positive number when a > b and zero when a == b.
SortFunc requires that cmp is a strict weak ordering. See https://en.wikipedia.org/wiki/Weak_ordering#Strict_weak_orderings.
Example (CaseInsensitive) ¶
package main
import (
"cmp"
"fmt"
"slices"
"strings"
)
func main() {
names := []string{"Bob", "alice", "VERA"}
slices.SortFunc(names, func(a, b string) int {
return cmp.Compare(strings.ToLower(a), strings.ToLower(b))
})
fmt.Println(names)
}
Output: [alice Bob VERA]
Example (MultiField) ¶
package main
import (
"cmp"
"fmt"
"slices"
)
func main() {
type Person struct {
Name string
Age int
}
people := []Person{
{"Gopher", 13},
{"Alice", 55},
{"Bob", 24},
{"Alice", 20},
}
slices.SortFunc(people, func(a, b Person) int {
if n := cmp.Compare(a.Name, b.Name); n != 0 {
return n
}
// If names are equal, order by age
return cmp.Compare(a.Age, b.Age)
})
fmt.Println(people)
}
Output: [{Alice 20} {Alice 55} {Bob 24} {Gopher 13}]
func SortStableFunc ¶
SortStableFunc sorts the slice x while keeping the original order of equal elements, using cmp to compare elements in the same way as SortFunc.
Example ¶
package main
import (
"cmp"
"fmt"
"slices"
)
func main() {
type Person struct {
Name string
Age int
}
people := []Person{
{"Gopher", 13},
{"Alice", 20},
{"Bob", 24},
{"Alice", 55},
}
// Stable sort by name, keeping age ordering of Alices intact
slices.SortStableFunc(people, func(a, b Person) int {
return cmp.Compare(a.Name, b.Name)
})
fmt.Println(people)
}
Output: [{Alice 20} {Alice 55} {Bob 24} {Gopher 13}]
Types ¶
This section is empty.
Source Files