1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
package utils
import "golang.org/x/exp/slices"
// NextIndex returns the index of the element that comes after the given number
func NextIndex(numbers []int, currentNumber int) int {
for index, number := range numbers {
if number > currentNumber {
return index
}
}
return len(numbers) - 1
}
// PrevIndex returns the index that comes before the given number, cycling if we reach the end
func PrevIndex(numbers []int, currentNumber int) int {
end := len(numbers) - 1
for i := end; i >= 0; i-- {
if numbers[i] < currentNumber {
return i
}
}
return 0
}
// NextIntInCycle returns the next int in a slice, returning to the first index if we've reached the end
func NextIntInCycle(sl []int, current int) int {
for i, val := range sl {
if val == current {
if i == len(sl)-1 {
return sl[0]
}
return sl[i+1]
}
}
return sl[0]
}
// PrevIntInCycle returns the prev int in a slice, returning to the first index if we've reached the end
func PrevIntInCycle(sl []int, current int) int {
for i, val := range sl {
if val == current {
if i > 0 {
return sl[i-1]
}
return sl[len(sl)-1]
}
}
return sl[len(sl)-1]
}
func StringArraysOverlap(strArrA []string, strArrB []string) bool {
for _, first := range strArrA {
for _, second := range strArrB {
if first == second {
return true
}
}
}
return false
}
func Limit(values []string, limit int) []string {
if len(values) > limit {
return values[:limit]
}
return values
}
func LimitStr(value string, limit int) string {
n := 0
for i := range value {
if n >= limit {
return value[:i]
}
n++
}
return value
}
// Similar to a regular GroupBy, except that each item can be grouped under multiple keys,
// so the callback returns a slice of keys instead of just one key.
func MuiltiGroupBy[T any, K comparable](slice []T, f func(T) []K) map[K][]T {
result := map[K][]T{}
for _, item := range slice {
for _, key := range f(item) {
if _, ok := result[key]; !ok {
result[key] = []T{item}
} else {
result[key] = append(result[key], item)
}
}
}
return result
}
// Returns a new slice with the element at index 'from' moved to index 'to'.
// Does not mutate original slice.
func MoveElement[T any](slice []T, from int, to int) []T {
newSlice := make([]T, len(slice))
copy(newSlice, slice)
if from == to {
return newSlice
}
if from < to {
copy(newSlice[from:to+1], newSlice[from+1:to+1])
} else {
copy(newSlice[to+1:from+1], newSlice[to:from])
}
newSlice[to] = slice[from]
return newSlice
}
func ValuesAtIndices[T any](slice []T, indices []int) []T {
result := make([]T, len(indices))
for i, index := range indices {
// gracefully handling the situation where the index is out of bounds
if index < len(slice) {
result[i] = slice[index]
}
}
return result
}
// returns two slices: the first is for elements that pass the test, the second for those that don't.
func Partition[T any](slice []T, test func(T) bool) ([]T, []T) {
left := make([]T, 0, len(slice))
right := make([]T, 0, len(slice))
for _, value := range slice {
if test(value) {
left = append(left, value)
} else {
right = append(right, value)
}
}
return left, right
}
// Prepends items to the beginning of a slice.
// E.g. Prepend([]int{1,2}, 3, 4) = []int{3,4,1,2}
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Prepend[T any](slice []T, values ...T) []T {
return append(values, slice...)
}
// Removes the element at the given index. Intended usage is to reassign the result to the input slice.
func Remove[T any](slice []T, index int) []T {
return slices.Delete(slice, index, index+1)
}
// Removes the element at the 'fromIndex' and then inserts it at 'toIndex'.
// Operates on the input slice. Expected use is to reassign the result to the input slice.
func Move[T any](slice []T, fromIndex int, toIndex int) []T {
item := slice[fromIndex]
slice = Remove(slice, fromIndex)
return slices.Insert(slice, toIndex, item)
}
// Pops item from the end of the slice and returns it, along with the updated slice
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Pop[T any](slice []T) (T, []T) {
index := len(slice) - 1
value := slice[index]
slice = slice[0:index]
return value, slice
}
// Shifts item from the beginning of the slice and returns it, along with the updated slice.
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Shift[T any](slice []T) (T, []T) {
value := slice[0]
slice = slice[1:]
return value, slice
}
|
