package slices
import "slices"
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 Concat[S ~[]E, E any](slices ...S) S
- 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 ¶
- BinarySearch
- BinarySearchFunc
- Compact
- CompactFunc
- Compare
- CompareFunc
- ContainsFunc
- Delete
- DeleteFunc
- Equal
- EqualFunc
- Index
- IndexFunc
- Insert
- IsSorted
- IsSortedFunc
- Max
- MaxFunc
- Min
- MinFunc
- Replace
- Reverse
- Sort
- SortFunc (CaseInsensitive)
- SortFunc (MultiField)
- SortStableFunc
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.
Code:play
Output: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)
}
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.
Code:play
Output: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)
}
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. Compact zeroes the elements between the new length and the original length.
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. CompactFunc zeroes the elements between the new length and the original length.
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.
Code:play
Output: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"}))
}
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).
Code:play
Output: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)
}
1
func Concat ¶
func Concat[S ~[]E, E any](slices ...S) S
Concat returns a new slice concatenating the passed in slices.
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).
Code:play
Output: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)
}
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 j > len(s) or s[i:j] is not a valid slice of s. Delete is O(len(s)-i), 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 zeroes the elements s[len(s)-(j-i):len(s)].
func DeleteFunc ¶
DeleteFunc removes any elements from s for which del returns true, returning the modified slice. DeleteFunc zeroes the elements between the new length and the original length.
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.
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.
Code:play
Output: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)
}
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.
func IndexFunc ¶
IndexFunc returns the first index i satisfying f(s[i]), or -1 if none do.
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)).
func IsSorted ¶
IsSorted reports whether x is sorted in ascending order.
func IsSortedFunc ¶
IsSortedFunc reports whether x is sorted in ascending order, with cmp as the
comparison function as defined by SortFunc.
Code:play
Output: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))
}
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).
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.
Code:play
Output: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)
}
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).
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.
Code:play
Output: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)
}
Bob
func Replace ¶
Replace replaces the elements s[i:j] by the given v, and returns the modified slice. Replace panics if j > len(s) or s[i:j] is not a valid slice of s. When len(v) < (j-i), Replace zeroes the elements between the new length and the original length.
func Reverse ¶
func Reverse[S ~[]E, E any](s S)
Reverse reverses the elements of the slice in place.
func Sort ¶
Sort sorts a slice of any ordered type in ascending order. When sorting floating-point numbers, NaNs are ordered before other values.
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.
Code:play
Output: Code:play
Output: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)
}
[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)
}
[{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.
Code:play
Output: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)
}
[{Alice 20} {Alice 55} {Bob 24} {Gopher 13}]
Source Files ¶
slices.go sort.go zsortanyfunc.go zsortordered.go
- Version
- v1.22.0-rc.1
- Published
- Dec 19, 2023
- Platform
- js/wasm
- Imports
- 3 packages
- Last checked
- 1 minute ago –
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