30-seconds-of-python-code

Python implementation of 30-seconds-of-code.

Note:- This is in no way affiliated with the original 30-seconds-of-code.

chunk

Chunks an array into smaller lists of a specified size.

Uses range to create a list of desired size. Then use map on this list and fill it with splices of arr.

from math import ceil


def chunk(arr, size):
    return list(
        map(lambda x: arr[x * size:x * size + size],
            list(range(0, ceil(len(arr) / size)))))

chunk([1,2,3,4,5],2) # [[1,2],[3,4],5]

count_occurences

Counts the occurrences of a value in an list.

Uses the reduce functin from built-in module functools to increment a counter each time you encounter the specific value inside the list.

def count_occurences(arr, val):
    return reduce(
        (lambda x, y: x + 1 if y == val and type(y) == type(val) else x + 0),
        arr)

count_occurrences([1, 1, 2, 1, 2, 3], 1) # 3

count_vowels

Retuns number of vowels in provided string.

Use a regular expression to count the number of vowels (A, E, I, O, U) in a string.

import re


def count_vowels(str):
    return len(len(re.findall(r'[aeiou]', str, re.IGNORECASE)))

count_vowels('foobar') # 3
count_vowels('gym') # 0

deep_flatten

Deep flattens a list.

Use recursion. Use list.extend() with an empty array (result) and the spread function to flatten a list. Recursively flatten each element that is a list.

def spread(arg):
    ret = []
    for i in arg:
        if isinstance(i, list):
            ret.extend(i)
        else:
            ret.append(i)
    return ret

 def deep_flatten(arr):
    result = []
    result.extend(spread(list(map(lambda x : deep(x) if type(x) == list else x,arr))))
    return result

deep_flatten([1, [2], [[3], 4], 5]) # [1,2,3,4,5]

gcd

Calculates the greatest common divisor between two or more numbers/lists.

The helperGcdfunction uses recursion. Base case is when y equals 0. In this case, return x. Otherwise, return the GCD of y and the remainder of the division x/y.

Uses the reduce function from the inbuilt module functools. Also defines a method spread for javascript like spreading of lists.

from functools import reduce


def spread(arg):
    ret = []
    for i in arg:
        if isinstance(i, list):
            ret.extend(i)
        else:
            ret.append(i)
    return ret


def gcd(*args):
    numbers = []
    numbers.extend(spread(list(args)))

    def _gcd(x, y):
        return x if not y else gcd(y, x % y)

    return reduce((lambda x, y: _gcd(x, y)), numbers)

gcd(8,36) # 4

lcm

Returns the least common multiple of two or more numbers.

Use the greatest common divisor (GCD) formula and the fact that lcm(x,y) = x * y / gcd(x,y) to determine the least common multiple. The GCD formula uses recursion.

Uses reduce function from the inbuilt module functools. Also defines a method spread for javascript like spreading of lists.

from functools import reduce


def spread(arg):
    ret = []
    for i in arg:
        if isinstance(i, list):
            ret.extend(i)
        else:
            ret.append(i)
    return ret


def lcm(*args):
    numbers = []
    numbers.extend(spread(list(args)))

    def _gcd(x, y):
        return x if not y else gcd(y, x % y)

    def _lcm(x, y):
        return x * y / _gcd(x, y)

    return reduce((lambda x, y: _lcm(x, y)), numbers)

lcm(12, 7) # 84
lcm([1, 3, 4], 5) # 60

spread

Implements javascript's spread syntax as a function. Flattens the list(non-deep) and returns an list.

def spread(arg):
    ret = []
    for i in arg:
        if isinstance(i, list):
            ret.extend(i)
        else:
            ret.append(i)
    return ret

spread([1,2,3,[4,5,6],[7],8,9]) # [1,2,3,4,5,6,7,8,9]

Credits

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