Python Tips

Posted on Wednesday, Jul 01, 2020 in programming • Tagged with python, tips, lists, functools, itertools, timezone

A collection of small Python scripts and tips.

This post is based on a Twitter thread I started in April 2020 and works as a centralized way to read all the tips in an easier format than Twitter's 280 characters.

Both will be updated frequently.

List Flatten without explicit loops

  • Using Itertools' chain
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import itertools

test = [[-1, -2], [30, 40], [25, 35]]
list(itertools.chain.from_iterable(test))

>>  [-1, -2, 30, 40, 25, 35]

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test =  [[-1, -2], [30, 40], [25, 35]]
map(int, ''.join(c for c in test.__str__() if c not in '[]').split(',') )

>> [-1, -2, 30, 40, 25, 35]

Not pretty in my opinion ;)

Count individual items of any iterable

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from collections import Counter
count = Counter(['a', 'b', 'c', 'a', 'a', 'b', 'd'])

print(count)
>> Counter({'a': 3, 'b': 2, 'c': 1, 'd': 1})

count['a']
>> 3

Repeat a series of values from any iterable

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import itertools as it

data = it.cycle([1, 2])

for i in range(10):
    print(next(data))

>> 1
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2

Name slices to reuse them

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# slice(start, end, step)

STEPTWO = slice(None, None, 2)
integer_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

integer_list[STEPTWO]

>> [0, 2, 4, 6, 8]

This is the same as:

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integer_list[::2]

Reverse any "indexable" collection that supports slices

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# slice(None, None, -1) or [::-1]

integer_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
integer_list[::-1]

>> [9, 8, 7, 6, 5 …

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