README
¶
itertools
Itertools is a tool kit to generate combinations and permutations of go slices. It works similar to python itertools.
Installation
go get -u github.com/ernestosuarez/itertools
Usage (Examples)
After installation the package has to be imported.
import "github.com/ernestosuarez/itertools"
###Generating combinations Slices of integers
// combinations of r = 3 elements chosen from iterable
r := 3
iterable := []int{1, 2, 3, 4 }
for v := range CombinationsInt(iterable, r) {
fmt.Println(v)
output:
[1 2 3]
[1 2 4]
[1 3 4]
[2 3 4]
Slices of strings
// combinations of r = 3 elements chosen from iterable
r := 3
iterable := []string{"A", "B", "C", "D"}
for v := range CombinationsStr(iterable, r) {
fmt.Println(v)
output:
[A B C]
[A B D]
[A C D]
[B C D]
Custom type List
Notice you have to use the right function depending of the type of the slice. For a more general case the user could define a custom type List as follows:
type List []interface{}
Then can create a list of heterogeneous types and follow the same procedure. In this case CombinationsList has to be used.
r := 3
myList := List{1, "B", 3, 3.14}
for v := range CombinationsList(myList, r) {
fmt.Println(v)
output:
[1 B 3]
[1 B 3.14]
[1 3 3.14]
[B 3 3.14]
###Generating permutations Slices of integers
If the number (r) of chosen element is equal to the length of the iterable, then we will obtain the r-factorial permutations
// permutations of r = 3 elements chosen from iterable with length 3
r := 3
iterable := []int{1, 2, 3}
for v := range PermutationsInt(iterable, r) {
fmt.Println(v)
output:
[1 2 3]
[1 3 2]
[2 1 3]
[2 3 1]
[3 1 2]
[3 2 1]
On the other hand we can chose less than len(iterable) elements
// permutations of r = 3 elements chosen from a iterable of length 4
r := 3
iterable := []int{1, 2, 3, 4}
for v := range CombinationsInt(iterable, r) {
fmt.Println(v)
output:
[1 2 3]
[1 3 2]
[2 1 3]
[2 3 1]
[3 1 2]
[3 2 1]
[1 2 4]
[1 4 2]
[2 1 4]
[2 4 1]
[4 1 2]
[4 2 1]
[1 3 4]
[1 4 3]
[3 1 4]
[3 4 1]
[4 1 3]
[4 3 1]
[2 3 4]
[2 4 3]
[3 2 4]
[3 4 2]
[4 2 3]
[4 3 2]
Slices of strings
Same idea, just use the function PermutationsStr
Custom type List
Same as in combinations, fist define the new type List (see above) and then use PermutationsList
Contributions
Contributions are welcome!
Documentation
¶
Index ¶
- func CombinationsInt(iterable []int, r int) chan []int
- func CombinationsList(iterable List, r int) chan List
- func CombinationsStr(iterable []string, r int) chan []string
- func GenCombinations(n, r int) <-chan []int
- func GenPermutations(n int) <-chan []int
- func PermutationsInt(iterable []int, r int) chan []int
- func PermutationsList(iterable List, r int) chan List
- func PermutationsStr(iterable []string, r int) chan []string
- type List
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func CombinationsInt ¶
CombinationsInt generates all the combinations of r elements extracted from an slice of integers
func CombinationsList ¶
CombinationsList generates all the combinations of r elements extracted from a List (an arbitrary list of elements). A List can be created for instance, as follows myList := List{"a", "b", 13, 3.523}
func CombinationsStr ¶
CombinationsStr generates all the combinations of r elements extracted from an slice of strings
func GenCombinations ¶
GenCombinations generates, from two natural numbers n > r, all the possible combinations of r indexes taken from 0 to n-1. For example if n=3 and r=2, the result will be: [0,1], [0,2] and [1,2]
func GenPermutations ¶
GenPermutations generates, given a number n, all the n factorial permutations of the integers from 0 to n-1
func PermutationsInt ¶
PermutationsInt generates all the permutations of r elements extracted from an slice of integers
func PermutationsList ¶
PermutationsList generates all the permutations of r elements extracted from a List (an arbitrary list of elements). A List can be created, for instance, as follows: myList := List{"a", "b", 13, 3.523}
func PermutationsStr ¶
PermutationsStr generates all the permutations of r elements extracted from an slice of strings
Source Files