From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/go/sort%2Findex.html | 648 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 648 insertions(+) create mode 100644 devdocs/go/sort%2Findex.html (limited to 'devdocs/go/sort%2Findex.html') diff --git a/devdocs/go/sort%2Findex.html b/devdocs/go/sort%2Findex.html new file mode 100644 index 00000000..3e37b155 --- /dev/null +++ b/devdocs/go/sort%2Findex.html @@ -0,0 +1,648 @@ +

Package sort

Overview

Package sort provides primitives for sorting slices and user-defined collections.

Example +

Code:

package sort_test
+
+import (
+    "fmt"
+    "sort"
+)
+
+type Person struct {
+    Name string
+    Age  int
+}
+
+func (p Person) String() string {
+    return fmt.Sprintf("%s: %d", p.Name, p.Age)
+}
+
+// ByAge implements sort.Interface for []Person based on
+// the Age field.
+type ByAge []Person
+
+func (a ByAge) Len() int           { return len(a) }
+func (a ByAge) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a ByAge) Less(i, j int) bool { return a[i].Age < a[j].Age }
+
+func Example() {
+    people := []Person{
+        {"Bob", 31},
+        {"John", 42},
+        {"Michael", 17},
+        {"Jenny", 26},
+    }
+
+    fmt.Println(people)
+    // There are two ways to sort a slice. First, one can define
+    // a set of methods for the slice type, as with ByAge, and
+    // call sort.Sort. In this first example we use that technique.
+    sort.Sort(ByAge(people))
+    fmt.Println(people)
+
+    // The other way is to use sort.Slice with a custom Less
+    // function, which can be provided as a closure. In this
+    // case no methods are needed. (And if they exist, they
+    // are ignored.) Here we re-sort in reverse order: compare
+    // the closure with ByAge.Less.
+    sort.Slice(people, func(i, j int) bool {
+        return people[i].Age > people[j].Age
+    })
+    fmt.Println(people)
+
+    // Output:
+    // [Bob: 31 John: 42 Michael: 17 Jenny: 26]
+    // [Michael: 17 Jenny: 26 Bob: 31 John: 42]
+    // [John: 42 Bob: 31 Jenny: 26 Michael: 17]
+}
+

Example (SortKeys) +

ExampleSortKeys demonstrates a technique for sorting a struct type using programmable sort criteria.

Code:

package sort_test
+
+import (
+    "fmt"
+    "sort"
+)
+
+// A couple of type definitions to make the units clear.
+type earthMass float64
+type au float64
+
+// A Planet defines the properties of a solar system object.
+type Planet struct {
+    name     string
+    mass     earthMass
+    distance au
+}
+
+// By is the type of a "less" function that defines the ordering of its Planet arguments.
+type By func(p1, p2 *Planet) bool
+
+// Sort is a method on the function type, By, that sorts the argument slice according to the function.
+func (by By) Sort(planets []Planet) {
+    ps := &planetSorter{
+        planets: planets,
+        by:      by, // The Sort method's receiver is the function (closure) that defines the sort order.
+    }
+    sort.Sort(ps)
+}
+
+// planetSorter joins a By function and a slice of Planets to be sorted.
+type planetSorter struct {
+    planets []Planet
+    by      func(p1, p2 *Planet) bool // Closure used in the Less method.
+}
+
+// Len is part of sort.Interface.
+func (s *planetSorter) Len() int {
+    return len(s.planets)
+}
+
+// Swap is part of sort.Interface.
+func (s *planetSorter) Swap(i, j int) {
+    s.planets[i], s.planets[j] = s.planets[j], s.planets[i]
+}
+
+// Less is part of sort.Interface. It is implemented by calling the "by" closure in the sorter.
+func (s *planetSorter) Less(i, j int) bool {
+    return s.by(&s.planets[i], &s.planets[j])
+}
+
+var planets = []Planet{
+    {"Mercury", 0.055, 0.4},
+    {"Venus", 0.815, 0.7},
+    {"Earth", 1.0, 1.0},
+    {"Mars", 0.107, 1.5},
+}
+
+// ExampleSortKeys demonstrates a technique for sorting a struct type using programmable sort criteria.
+func Example_sortKeys() {
+    // Closures that order the Planet structure.
+    name := func(p1, p2 *Planet) bool {
+        return p1.name < p2.name
+    }
+    mass := func(p1, p2 *Planet) bool {
+        return p1.mass < p2.mass
+    }
+    distance := func(p1, p2 *Planet) bool {
+        return p1.distance < p2.distance
+    }
+    decreasingDistance := func(p1, p2 *Planet) bool {
+        return distance(p2, p1)
+    }
+
+    // Sort the planets by the various criteria.
+    By(name).Sort(planets)
+    fmt.Println("By name:", planets)
+
+    By(mass).Sort(planets)
+    fmt.Println("By mass:", planets)
+
+    By(distance).Sort(planets)
+    fmt.Println("By distance:", planets)
+
+    By(decreasingDistance).Sort(planets)
+    fmt.Println("By decreasing distance:", planets)
+
+    // Output: By name: [{Earth 1 1} {Mars 0.107 1.5} {Mercury 0.055 0.4} {Venus 0.815 0.7}]
+    // By mass: [{Mercury 0.055 0.4} {Mars 0.107 1.5} {Venus 0.815 0.7} {Earth 1 1}]
+    // By distance: [{Mercury 0.055 0.4} {Venus 0.815 0.7} {Earth 1 1} {Mars 0.107 1.5}]
+    // By decreasing distance: [{Mars 0.107 1.5} {Earth 1 1} {Venus 0.815 0.7} {Mercury 0.055 0.4}]
+}
+

Example (SortMultiKeys) +

ExampleMultiKeys demonstrates a technique for sorting a struct type using different sets of multiple fields in the comparison. We chain together "Less" functions, each of which compares a single field.

Code:

package sort_test
+
+import (
+    "fmt"
+    "sort"
+)
+
+// A Change is a record of source code changes, recording user, language, and delta size.
+type Change struct {
+    user     string
+    language string
+    lines    int
+}
+
+type lessFunc func(p1, p2 *Change) bool
+
+// multiSorter implements the Sort interface, sorting the changes within.
+type multiSorter struct {
+    changes []Change
+    less    []lessFunc
+}
+
+// Sort sorts the argument slice according to the less functions passed to OrderedBy.
+func (ms *multiSorter) Sort(changes []Change) {
+    ms.changes = changes
+    sort.Sort(ms)
+}
+
+// OrderedBy returns a Sorter that sorts using the less functions, in order.
+// Call its Sort method to sort the data.
+func OrderedBy(less ...lessFunc) *multiSorter {
+    return &multiSorter{
+        less: less,
+    }
+}
+
+// Len is part of sort.Interface.
+func (ms *multiSorter) Len() int {
+    return len(ms.changes)
+}
+
+// Swap is part of sort.Interface.
+func (ms *multiSorter) Swap(i, j int) {
+    ms.changes[i], ms.changes[j] = ms.changes[j], ms.changes[i]
+}
+
+// Less is part of sort.Interface. It is implemented by looping along the
+// less functions until it finds a comparison that discriminates between
+// the two items (one is less than the other). Note that it can call the
+// less functions twice per call. We could change the functions to return
+// -1, 0, 1 and reduce the number of calls for greater efficiency: an
+// exercise for the reader.
+func (ms *multiSorter) Less(i, j int) bool {
+    p, q := &ms.changes[i], &ms.changes[j]
+    // Try all but the last comparison.
+    var k int
+    for k = 0; k < len(ms.less)-1; k++ {
+        less := ms.less[k]
+        switch {
+        case less(p, q):
+            // p < q, so we have a decision.
+            return true
+        case less(q, p):
+            // p > q, so we have a decision.
+            return false
+        }
+        // p == q; try the next comparison.
+    }
+    // All comparisons to here said "equal", so just return whatever
+    // the final comparison reports.
+    return ms.less[k](p, q)
+}
+
+var changes = []Change{
+    {"gri", "Go", 100},
+    {"ken", "C", 150},
+    {"glenda", "Go", 200},
+    {"rsc", "Go", 200},
+    {"r", "Go", 100},
+    {"ken", "Go", 200},
+    {"dmr", "C", 100},
+    {"r", "C", 150},
+    {"gri", "Smalltalk", 80},
+}
+
+// ExampleMultiKeys demonstrates a technique for sorting a struct type using different
+// sets of multiple fields in the comparison. We chain together "Less" functions, each of
+// which compares a single field.
+func Example_sortMultiKeys() {
+    // Closures that order the Change structure.
+    user := func(c1, c2 *Change) bool {
+        return c1.user < c2.user
+    }
+    language := func(c1, c2 *Change) bool {
+        return c1.language < c2.language
+    }
+    increasingLines := func(c1, c2 *Change) bool {
+        return c1.lines < c2.lines
+    }
+    decreasingLines := func(c1, c2 *Change) bool {
+        return c1.lines > c2.lines // Note: > orders downwards.
+    }
+
+    // Simple use: Sort by user.
+    OrderedBy(user).Sort(changes)
+    fmt.Println("By user:", changes)
+
+    // More examples.
+    OrderedBy(user, increasingLines).Sort(changes)
+    fmt.Println("By user,<lines:", changes)
+
+    OrderedBy(user, decreasingLines).Sort(changes)
+    fmt.Println("By user,>lines:", changes)
+
+    OrderedBy(language, increasingLines).Sort(changes)
+    fmt.Println("By language,<lines:", changes)
+
+    OrderedBy(language, increasingLines, user).Sort(changes)
+    fmt.Println("By language,<lines,user:", changes)
+
+    // Output:
+    // By user: [{dmr C 100} {glenda Go 200} {gri Go 100} {gri Smalltalk 80} {ken C 150} {ken Go 200} {r Go 100} {r C 150} {rsc Go 200}]
+    // By user,<lines: [{dmr C 100} {glenda Go 200} {gri Smalltalk 80} {gri Go 100} {ken C 150} {ken Go 200} {r Go 100} {r C 150} {rsc Go 200}]
+    // By user,>lines: [{dmr C 100} {glenda Go 200} {gri Go 100} {gri Smalltalk 80} {ken Go 200} {ken C 150} {r C 150} {r Go 100} {rsc Go 200}]
+    // By language,<lines: [{dmr C 100} {ken C 150} {r C 150} {gri Go 100} {r Go 100} {glenda Go 200} {ken Go 200} {rsc Go 200} {gri Smalltalk 80}]
+    // By language,<lines,user: [{dmr C 100} {ken C 150} {r C 150} {gri Go 100} {r Go 100} {glenda Go 200} {ken Go 200} {rsc Go 200} {gri Smalltalk 80}]
+
+}
+

Example (SortWrapper) +

Code:

package sort_test
+
+import (
+    "fmt"
+    "sort"
+)
+
+type Grams int
+
+func (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }
+
+type Organ struct {
+    Name   string
+    Weight Grams
+}
+
+type Organs []*Organ
+
+func (s Organs) Len() int      { return len(s) }
+func (s Organs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+// ByName implements sort.Interface by providing Less and using the Len and
+// Swap methods of the embedded Organs value.
+type ByName struct{ Organs }
+
+func (s ByName) Less(i, j int) bool { return s.Organs[i].Name < s.Organs[j].Name }
+
+// ByWeight implements sort.Interface by providing Less and using the Len and
+// Swap methods of the embedded Organs value.
+type ByWeight struct{ Organs }
+
+func (s ByWeight) Less(i, j int) bool { return s.Organs[i].Weight < s.Organs[j].Weight }
+
+func Example_sortWrapper() {
+    s := []*Organ{
+        {"brain", 1340},
+        {"heart", 290},
+        {"liver", 1494},
+        {"pancreas", 131},
+        {"prostate", 62},
+        {"spleen", 162},
+    }
+
+    sort.Sort(ByWeight{s})
+    fmt.Println("Organs by weight:")
+    printOrgans(s)
+
+    sort.Sort(ByName{s})
+    fmt.Println("Organs by name:")
+    printOrgans(s)
+
+    // Output:
+    // Organs by weight:
+    // prostate (62g)
+    // pancreas (131g)
+    // spleen   (162g)
+    // heart    (290g)
+    // brain    (1340g)
+    // liver    (1494g)
+    // Organs by name:
+    // brain    (1340g)
+    // heart    (290g)
+    // liver    (1494g)
+    // pancreas (131g)
+    // prostate (62g)
+    // spleen   (162g)
+}
+
+func printOrgans(s []*Organ) {
+    for _, o := range s {
+        fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)
+    }
+}
+

Index

Examples

Package
Float64s
Float64sAreSorted
Ints
IntsAreSorted
Reverse
Search
SearchFloat64s
SearchInts
Search (DescendingOrder)
Slice
SliceStable
Strings
Package (SortKeys)
Package (SortMultiKeys)
Package (SortWrapper)

Package files

search.go slice.go sort.go sort_impl_go121.go zsortfunc.go zsortinterface.go

func Find 1.19 

func Find(n int, cmp func(int) int) (i int, found bool)

Find uses binary search to find and return the smallest index i in [0, n) at which cmp(i) <= 0. If there is no such index i, Find returns i = n. The found result is true if i < n and cmp(i) == 0. Find calls cmp(i) only for i in the range [0, n).

+

To permit binary search, Find requires that cmp(i) > 0 for a leading prefix of the range, cmp(i) == 0 in the middle, and cmp(i) < 0 for the final suffix of the range. (Each subrange could be empty.) The usual way to establish this condition is to interpret cmp(i) as a comparison of a desired target value t against entry i in an underlying indexed data structure x, returning <0, 0, and >0 when t < x[i], t == x[i], and t > x[i], respectively.

+

For example, to look for a particular string in a sorted, random-access list of strings:

+
i, found := sort.Find(x.Len(), func(i int) int {
+    return strings.Compare(target, x.At(i))
+})
+if found {
+    fmt.Printf("found %s at entry %d\n", target, i)
+} else {
+    fmt.Printf("%s not found, would insert at %d", target, i)
+}
+

func Float64s 

func Float64s(x []float64)

Float64s sorts a slice of float64s in increasing order. Not-a-number (NaN) values are ordered before other values.

+

Note: as of Go 1.22, this function simply calls slices.Sort.

Example +

Code:

s := []float64{5.2, -1.3, 0.7, -3.8, 2.6} // unsorted
+sort.Float64s(s)
+fmt.Println(s)
+
+s = []float64{math.Inf(1), math.NaN(), math.Inf(-1), 0.0} // unsorted
+sort.Float64s(s)
+fmt.Println(s)
+
+

Output:

[-3.8 -1.3 0.7 2.6 5.2]
+[NaN -Inf 0 +Inf]
+

func Float64sAreSorted 

func Float64sAreSorted(x []float64) bool

Float64sAreSorted reports whether the slice x is sorted in increasing order, with not-a-number (NaN) values before any other values.

+

Note: as of Go 1.22, this function simply calls slices.IsSorted.

Example +

Code:

s := []float64{0.7, 1.3, 2.6, 3.8, 5.2} // sorted ascending
+fmt.Println(sort.Float64sAreSorted(s))
+
+s = []float64{5.2, 3.8, 2.6, 1.3, 0.7} // sorted descending
+fmt.Println(sort.Float64sAreSorted(s))
+
+s = []float64{5.2, 1.3, 0.7, 3.8, 2.6} // unsorted
+fmt.Println(sort.Float64sAreSorted(s))
+
+

Output:

true
+false
+false
+

func Ints 

func Ints(x []int)

Ints sorts a slice of ints in increasing order.

+

Note: as of Go 1.22, this function simply calls slices.Sort.

Example +

Code:

s := []int{5, 2, 6, 3, 1, 4} // unsorted
+sort.Ints(s)
+fmt.Println(s)
+

Output:

[1 2 3 4 5 6]
+

func IntsAreSorted 

func IntsAreSorted(x []int) bool

IntsAreSorted reports whether the slice x is sorted in increasing order.

+

Note: as of Go 1.22, this function simply calls slices.IsSorted.

Example +

Code:

s := []int{1, 2, 3, 4, 5, 6} // sorted ascending
+fmt.Println(sort.IntsAreSorted(s))
+
+s = []int{6, 5, 4, 3, 2, 1} // sorted descending
+fmt.Println(sort.IntsAreSorted(s))
+
+s = []int{3, 2, 4, 1, 5} // unsorted
+fmt.Println(sort.IntsAreSorted(s))
+
+

Output:

true
+false
+false
+

func IsSorted 

func IsSorted(data Interface) bool

IsSorted reports whether data is sorted.

+

Note: in many situations, the newer slices.IsSortedFunc function is more ergonomic and runs faster.

+ 
func Search(n int, f func(int) bool) int

Search uses binary search to find and return the smallest index i in [0, n) at which f(i) is true, assuming that on the range [0, n), f(i) == true implies f(i+1) == true. That is, Search requires that f is false for some (possibly empty) prefix of the input range [0, n) and then true for the (possibly empty) remainder; Search returns the first true index. If there is no such index, Search returns n. (Note that the "not found" return value is not -1 as in, for instance, strings.Index.) Search calls f(i) only for i in the range [0, n).

+

A common use of Search is to find the index i for a value x in a sorted, indexable data structure such as an array or slice. In this case, the argument f, typically a closure, captures the value to be searched for, and how the data structure is indexed and ordered.

+

For instance, given a slice data sorted in ascending order, the call Search(len(data), func(i int) bool { return data[i] >= 23 }) returns the smallest index i such that data[i] >= 23. If the caller wants to find whether 23 is in the slice, it must test data[i] == 23 separately.

+

Searching data sorted in descending order would use the <= operator instead of the >= operator.

+

To complete the example above, the following code tries to find the value x in an integer slice data sorted in ascending order:

+
x := 23
+i := sort.Search(len(data), func(i int) bool { return data[i] >= x })
+if i < len(data) && data[i] == x {
+	// x is present at data[i]
+} else {
+	// x is not present in data,
+	// but i is the index where it would be inserted.
+}
+

As a more whimsical example, this program guesses your number:

+
func GuessingGame() {
+	var s string
+	fmt.Printf("Pick an integer from 0 to 100.\n")
+	answer := sort.Search(100, func(i int) bool {
+		fmt.Printf("Is your number <= %d? ", i)
+		fmt.Scanf("%s", &s)
+		return s != "" && s[0] == 'y'
+	})
+	fmt.Printf("Your number is %d.\n", answer)
+}
+

This example demonstrates searching a list sorted in ascending order.

Code:

a := []int{1, 3, 6, 10, 15, 21, 28, 36, 45, 55}
+x := 6
+
+i := sort.Search(len(a), func(i int) bool { return a[i] >= x })
+if i < len(a) && a[i] == x {
+    fmt.Printf("found %d at index %d in %v\n", x, i, a)
+} else {
+    fmt.Printf("%d not found in %v\n", x, a)
+}
+

Output:

found 6 at index 2 in [1 3 6 10 15 21 28 36 45 55]
+

Example (DescendingOrder) +

This example demonstrates searching a list sorted in descending order. The approach is the same as searching a list in ascending order, but with the condition inverted.

Code:

a := []int{55, 45, 36, 28, 21, 15, 10, 6, 3, 1}
+x := 6
+
+i := sort.Search(len(a), func(i int) bool { return a[i] <= x })
+if i < len(a) && a[i] == x {
+    fmt.Printf("found %d at index %d in %v\n", x, i, a)
+} else {
+    fmt.Printf("%d not found in %v\n", x, a)
+}
+

Output:

found 6 at index 7 in [55 45 36 28 21 15 10 6 3 1]
+

func SearchFloat64s 

func SearchFloat64s(a []float64, x float64) int

SearchFloat64s searches for x in a sorted slice of float64s and returns the index as specified by Search. The return value is the index to insert x if x is not present (it could be len(a)). The slice must be sorted in ascending order.

Example +

This example demonstrates searching for float64 in a list sorted in ascending order.

Code:

a := []float64{1.0, 2.0, 3.3, 4.6, 6.1, 7.2, 8.0}
+
+x := 2.0
+i := sort.SearchFloat64s(a, x)
+fmt.Printf("found %g at index %d in %v\n", x, i, a)
+
+x = 0.5
+i = sort.SearchFloat64s(a, x)
+fmt.Printf("%g not found, can be inserted at index %d in %v\n", x, i, a)
+

Output:

found 2 at index 1 in [1 2 3.3 4.6 6.1 7.2 8]
+0.5 not found, can be inserted at index 0 in [1 2 3.3 4.6 6.1 7.2 8]
+

func SearchInts 

func SearchInts(a []int, x int) int

SearchInts searches for x in a sorted slice of ints and returns the index as specified by Search. The return value is the index to insert x if x is not present (it could be len(a)). The slice must be sorted in ascending order.

Example +

This example demonstrates searching for int in a list sorted in ascending order.

Code:

a := []int{1, 2, 3, 4, 6, 7, 8}
+
+x := 2
+i := sort.SearchInts(a, x)
+fmt.Printf("found %d at index %d in %v\n", x, i, a)
+
+x = 5
+i = sort.SearchInts(a, x)
+fmt.Printf("%d not found, can be inserted at index %d in %v\n", x, i, a)
+

Output:

found 2 at index 1 in [1 2 3 4 6 7 8]
+5 not found, can be inserted at index 4 in [1 2 3 4 6 7 8]
+

func SearchStrings 

func SearchStrings(a []string, x string) int

SearchStrings searches for x in a sorted slice of strings and returns the index as specified by Search. The return value is the index to insert x if x is not present (it could be len(a)). The slice must be sorted in ascending order.

+

func Slice 1.8 

func Slice(x any, less func(i, j int) bool)

Slice sorts the slice x given the provided less function. It panics if x is not a slice.

+

The sort is not guaranteed to be stable: equal elements may be reversed from their original order. For a stable sort, use SliceStable.

+

The less function must satisfy the same requirements as the Interface type's Less method.

+

Note: in many situations, the newer slices.SortFunc function is more ergonomic and runs faster.

Example +

Code:

people := []struct {
+    Name string
+    Age  int
+}{
+    {"Gopher", 7},
+    {"Alice", 55},
+    {"Vera", 24},
+    {"Bob", 75},
+}
+sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })
+fmt.Println("By name:", people)
+
+sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })
+fmt.Println("By age:", people)
+

Output:

By name: [{Alice 55} {Bob 75} {Gopher 7} {Vera 24}]
+By age: [{Gopher 7} {Vera 24} {Alice 55} {Bob 75}]
+

func SliceIsSorted 1.8 

func SliceIsSorted(x any, less func(i, j int) bool) bool

SliceIsSorted reports whether the slice x is sorted according to the provided less function. It panics if x is not a slice.

+

Note: in many situations, the newer slices.IsSortedFunc function is more ergonomic and runs faster.

+

func SliceStable 1.8 

func SliceStable(x any, less func(i, j int) bool)

SliceStable sorts the slice x using the provided less function, keeping equal elements in their original order. It panics if x is not a slice.

+

The less function must satisfy the same requirements as the Interface type's Less method.

+

Note: in many situations, the newer slices.SortStableFunc function is more ergonomic and runs faster.

Example +

Code:

people := []struct {
+    Name string
+    Age  int
+}{
+    {"Alice", 25},
+    {"Elizabeth", 75},
+    {"Alice", 75},
+    {"Bob", 75},
+    {"Alice", 75},
+    {"Bob", 25},
+    {"Colin", 25},
+    {"Elizabeth", 25},
+}
+
+// Sort by name, preserving original order
+sort.SliceStable(people, func(i, j int) bool { return people[i].Name < people[j].Name })
+fmt.Println("By name:", people)
+
+// Sort by age preserving name order
+sort.SliceStable(people, func(i, j int) bool { return people[i].Age < people[j].Age })
+fmt.Println("By age,name:", people)
+
+

Output:

By name: [{Alice 25} {Alice 75} {Alice 75} {Bob 75} {Bob 25} {Colin 25} {Elizabeth 75} {Elizabeth 25}]
+By age,name: [{Alice 25} {Bob 25} {Colin 25} {Elizabeth 25} {Alice 75} {Alice 75} {Bob 75} {Elizabeth 75}]
+

func Sort 

func Sort(data Interface)

Sort sorts data in ascending order as determined by the Less method. It makes one call to data.Len to determine n and O(n*log(n)) calls to data.Less and data.Swap. The sort is not guaranteed to be stable.

+

Note: in many situations, the newer slices.SortFunc function is more ergonomic and runs faster.

+

func Stable 1.2 

func Stable(data Interface)

Stable sorts data in ascending order as determined by the Less method, while keeping the original order of equal elements.

+

It makes one call to data.Len to determine n, O(n*log(n)) calls to data.Less and O(n*log(n)*log(n)) calls to data.Swap.

+

Note: in many situations, the newer slices.SortStableFunc function is more ergonomic and runs faster.

+

func Strings 

func Strings(x []string)

Strings sorts a slice of strings in increasing order.

+

Note: as of Go 1.22, this function simply calls slices.Sort.

Example +

Code:

s := []string{"Go", "Bravo", "Gopher", "Alpha", "Grin", "Delta"}
+sort.Strings(s)
+fmt.Println(s)
+

Output:

[Alpha Bravo Delta Go Gopher Grin]
+

func StringsAreSorted 

func StringsAreSorted(x []string) bool

StringsAreSorted reports whether the slice x is sorted in increasing order.

+

Note: as of Go 1.22, this function simply calls slices.IsSorted.

+

type Float64Slice

Float64Slice implements Interface for a []float64, sorting in increasing order, with not-a-number (NaN) values ordered before other values.

+
type Float64Slice []float64

func (Float64Slice) Len 

func (x Float64Slice) Len() int

func (Float64Slice) Less 

func (x Float64Slice) Less(i, j int) bool

Less reports whether x[i] should be ordered before x[j], as required by the sort Interface. Note that floating-point comparison by itself is not a transitive relation: it does not report a consistent ordering for not-a-number (NaN) values. This implementation of Less places NaN values before any others, by using:

+
x[i] < x[j] || (math.IsNaN(x[i]) && !math.IsNaN(x[j]))
+

func (Float64Slice) Search 

func (p Float64Slice) Search(x float64) int

Search returns the result of applying SearchFloat64s to the receiver and x.

+

func (Float64Slice) Sort 

func (x Float64Slice) Sort()

Sort is a convenience method: x.Sort() calls Sort(x).

+

func (Float64Slice) Swap 

func (x Float64Slice) Swap(i, j int)

type IntSlice

IntSlice attaches the methods of Interface to []int, sorting in increasing order.

+
type IntSlice []int

func (IntSlice) Len 

func (x IntSlice) Len() int

func (IntSlice) Less 

func (x IntSlice) Less(i, j int) bool

func (IntSlice) Search 

func (p IntSlice) Search(x int) int

Search returns the result of applying SearchInts to the receiver and x.

+

func (IntSlice) Sort 

func (x IntSlice) Sort()

Sort is a convenience method: x.Sort() calls Sort(x).

+

func (IntSlice) Swap 

func (x IntSlice) Swap(i, j int)

type Interface

An implementation of Interface can be sorted by the routines in this package. The methods refer to elements of the underlying collection by integer index.

+
type Interface interface {
+    // Len is the number of elements in the collection.
+    Len() int
+
+    // Less reports whether the element with index i
+    // must sort before the element with index j.
+    //
+    // If both Less(i, j) and Less(j, i) are false,
+    // then the elements at index i and j are considered equal.
+    // Sort may place equal elements in any order in the final result,
+    // while Stable preserves the original input order of equal elements.
+    //
+    // Less must describe a transitive ordering:
+    //  - if both Less(i, j) and Less(j, k) are true, then Less(i, k) must be true as well.
+    //  - if both Less(i, j) and Less(j, k) are false, then Less(i, k) must be false as well.
+    //
+    // Note that floating-point comparison (the < operator on float32 or float64 values)
+    // is not a transitive ordering when not-a-number (NaN) values are involved.
+    // See Float64Slice.Less for a correct implementation for floating-point values.
+    Less(i, j int) bool
+
+    // Swap swaps the elements with indexes i and j.
+    Swap(i, j int)
+}

func Reverse 1.1 

func Reverse(data Interface) Interface

Reverse returns the reverse order for data.

Example +

Code:

s := []int{5, 2, 6, 3, 1, 4} // unsorted
+sort.Sort(sort.Reverse(sort.IntSlice(s)))
+fmt.Println(s)
+

Output:

[6 5 4 3 2 1]
+

type StringSlice

StringSlice attaches the methods of Interface to []string, sorting in increasing order.

+
type StringSlice []string

func (StringSlice) Len 

func (x StringSlice) Len() int

func (StringSlice) Less 

func (x StringSlice) Less(i, j int) bool

func (StringSlice) Search 

func (p StringSlice) Search(x string) int

Search returns the result of applying SearchStrings to the receiver and x.

+

func (StringSlice) Sort 

func (x StringSlice) Sort()

Sort is a convenience method: x.Sort() calls Sort(x).

+

func (StringSlice) Swap 

func (x StringSlice) Swap(i, j int)
+

+ © Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
+ http://golang.org/pkg/sort/ +

+
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