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https://github.com/narimiran/itertools

Nim rewrite of a very popular Python module of the same name.
https://github.com/narimiran/itertools

iterators itertools nim nim-lang nimble

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Nim rewrite of a very popular Python module of the same name.

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# Itertools



This package is a Nim rewrite of a [very popular Python module](https://docs.python.org/3/library/itertools.html) of the same name.



It also includes some of the iterators from [iterutils](https://boltons.readthedocs.io/en/latest/iterutils.html).



 



## Installation



```

nimble install itertools

```



Required Nim version is at least 0.18.0.



 



## Supported iterators



* infinite iterators:

    * count

    * cycle

    * repeat



* terminating iterators:

    * accumulate

    * chain

    * compress

    * dropWhile

    * filterFalse

    * groupBy

    * groupConsecutive

    * islice

    * takeWhile



* combinatoric iterators:

    * product

    * distinctPermutations

    * permutations

    * combinations



* iterutils iterators:

    * chunked

    * windowed

    * pairwise

    * unique



 



## Usage



For more comprehensive examples, see the [documentation](https://narimiran.github.io/itertools).



### Infinite iterators



WARNING: Version 0.3.0 introduced breaking changes regarding how these three iterators are implemented and used.

See the examples below for the new behaviour.



```nim

import itertools



for i in count(5):

  if i > 9: break

  echo i

# 5; 6; 7; 8; 9



for i in count(100, 30):

  if i > 200: break

  echo i

# 100; 130; 160; 190



var n = 0

for i in @["I", "repeat", "myself"].cycle:

  inc n

  if n > 8: break

  echo i

# I; repeat; myself; I; repeat; myself; I; repeat



for i in "Beetlejuice".repeat(3):

  echo i

# Beetlejuice; Beetlejuice; Beetlejuice



var k = 0

for i in "forever".repeat:

  inc k

  if k > 6: break

  echo i

# forever; forever; forever; forever; forever; forever

```



### Terminating iterators



```nim

import itertools

import future # to use `=>` for anonymous proc



let # you can use: sequences, arrays, strings

  numbers = @[1, 3, 7, 8, 4, 2, 6, 5, 9]

  constants = [2.7183, 3.1416, 1.4142, 1.7321]

  word = "abracadabra"



for i in accumulate(constants, (x, y) => x + y):

  echo i

# 2.7183; 5.8599; 7.2741; 9.0062



for i in compress(numbers, [true, true, false, true, false, true]):

  echo i

# 1; 3; 8; 2



for i in dropWhile(numbers, x => (x != 8)):

  echo i

# 8; 4; 2; 6; 5; 9



for i in filterFalse(word, x => (x == 'a')):

  echo i

# b; r; c; d; b; r



for key, group in numbers.groupBy(x => x mod 2 == 0):

  echo "key: ", key, " group: ", group

# key: true, group: @[8, 4, 2, 6]; key: false, group: @[1, 3, 7, 5, 9]



for key, group in word.groupBy():

  echo group

# @['a', 'a', 'a', 'a', 'a']; @['b', 'b']; @['c']; @['d']; @['r', 'r']



for key, group in groupConsecutive("aaabaabb"):

  echo group

# @['a', 'a', 'a']; @['b']; @['a', 'a']; @['b', 'b']



for i in islice(numbers, 5):

  echo i

# 2; 6; 5; 9



for i in islice(word, 1, step=2):

  echo i

# b; a; a; a; r



for i in islice(numbers, stop=5, step=2):

  echo i

# 1; 7; 4



for i in takeWhile(constants, x => (x >= 2.0)):

  echo i

# 2.7183; 3.1416



for i in chain(@[1, 3, 5], @[2, 4, 6], @[7, 8, 9]):

  echo i

# 1; 3; 5; 2; 4; 6; 7; 8; 9

```



### Combinatoric iterators



```nim

import itertools

import strutils # to join seq[char] into a string



let # you can use: sequences, arrays, strings

  numbers = @[1, 3, 7, 8, 4]

  constants = [2.7183, 3.1416]

  word = "abba"



for i in product([0, 1], repeat = 3):

  echo i

# @[0, 0, 0]; @[0, 0, 1]; @[0, 1, 0]; @[0, 1, 1]; @[1, 0, 0]; @[1, 0, 1]; @[1, 1, 0]; @[1, 1, 1]



for i in product(numbers, constants):

  echo i

# (a: 1, b: 2.7183); (a: 1, b: 3.1416); (a: 3, b: 2.7183); (a: 3, b: 3.1416); (a: 7, b: 2.7183); (a: 7, b: 3.1416); (a: 8, b: 2.7183); (a: 8, b: 3.1416); (a: 4, b: 2.7183); (a: 4, b: 3.1416)



for i in distinctPermutations(word):

  echo i.join

# aabb; abab; abba; baab; baba; bbaa



for i in permutations(word):

  echo i.join

# abba; abab; abba; abab; aabb; aabb; baba; baab; bbaa; bbaa; baab; baba; baba; baab; bbaa; bbaa; baab; baba; aabb; aabb; abab; abba; abab; abba



for i in combinations(5, 3):

  echo i

# @[0, 1, 2]; @[0, 1, 3]; @[0, 1, 4]; @[0, 2, 3]; @[0, 2, 4]; @[0, 3, 4]; @[1, 2, 3]; @[1, 2, 4]; @[1, 3, 4]; @[2, 3, 4]



for i in combinations(numbers, 2):

  echo i

# @[1, 3]; @[1, 7]; @[1, 8]; @[1, 4]; @[3, 7]; @[3, 8]; @[3, 4]; @[7, 8]; @[7, 4]; @[8, 4]

```



### Iterutils iterators



```nim

import itertools



let # you can use: sequences, arrays, strings

  numbers = @[1, 3, 7, 8, 4, 2, 6, 5, 9]

  constants = [2.7183, 3.1416, 1.4142, 1.7321]

  word = "abracadabra"



for i in chunked(numbers, 3):

  echo i

# @[1, 3, 7]; @[8, 4, 2]; @[6, 5, 9]



for i in windowed(numbers, 4):

  echo i

# @[1, 3, 7, 8]; @[3, 7, 8, 4]; @[7, 8, 4, 2]; @[8, 4, 2, 6]; @[4, 2, 6, 5]; @[2, 6, 5, 9]



for i in pairwise(constants):

  echo i

# @[2.7183, 3.1416]; @[3.1416, 1.4142]; @[1.4142, 1.7321]



for i in unique(word):

  echo i

# a; b; r; c; d

```



 



## Contributing



There is probably a lot of room for improvement.

Feel free to fork the repo and submit your PRs.



Before submitting, run `nim doc -o:./docs/index.html ./src/itertools.nim` to make sure that all the asserts in `runnableExamples` are passing.



 



## License



[MIT license](LICENSE.txt)