Python one-liners

How to use one-liners to perform common tasks

import numpy as np

Flatten a list

x = np.random.randint(100, size=(4, 5))
[i for j in x for i in j]

[99, 46, 16, 16, 50, 19, 96, 63, 57, 6, 36, 81, 98, 87, 30, 42, 24, 72, 39, 7]

x = np.random.randint(5, size=10)
x

array([2, 0, 0, 2, 0, 4, 2, 4, 3, 1])

list(set(x))

[0, 1, 2, 3, 4]

x = np.random.randint(5, size=20)
x

array([0, 1, 0, 1, 4, 2, 4, 4, 2, 1, 4, 0, 2, 0, 1, 1, 1, 1, 3, 2])

from collections import Counter

Counter(x).most_common()

[(1, 7), (0, 4), (4, 4), (2, 4), (3, 1)]

Counter(x).most_common()[0]

(1, 7)

Counter(x).most_common()[0][0]

x = np.arange(1, 11)
x

array([ 1,  2,  3,  4,  5,  6,  7,  8,  9, 10])

np.prod(x)

from functools import reduce

reduce((lambda x,y: x*y), x)

myarray = np.random.randint(8, size=20)
myarray

array([0, 1, 0, 0, 3, 5, 1, 3, 0, 0, 6, 3, 0, 6, 1, 4, 1, 5, 6, 4])

np.where(myarray==1)[0]

array([ 1,  6, 14, 16])

mylist = list(np.random.randint(8, size=20))
mylist

[7, 0, 2, 3, 0, 1, 5, 5, 7, 3, 1, 2, 1, 2, 3, 5, 1, 2, 0, 4]

[i for i in range(len(mylist)) if mylist[i] == 1]

[5, 10, 12, 16]