Python Clean Code - Vish Blog

Some Python clean code examples.

1. Use iterators instead of index based for loops

Bad code

items = [1, 3, 5]
for i in range(len(items)):
    print(items[i])

Good code

items = [1, 3, 5]
for item in items:
    print(item)

2. Enumerate if you want the index

Bad code

items = [1, 3, 5]
for i in range(len(items)):
    print(i, items[i])

Good code

items = [1, 3, 5]
for i, item in enumerate(items):
    print(i, item)

3. Uze zip for iterating over two lists of same length

Bad code

items = [1, 3, 5]
other_items = [2, 4, 6]
for i in range(len(items)):
    print(items[i], other_items[i])

Good code

items = [1, 3, 5]
other_items = [2, 4, 6]

for item, other_item in zip(items, other_items):
    print(item, other_item)

4. List comprehension over raw for loops

Bad code

items = [1, 3, 5]
other_items = []
for item in items:
    other_items.append(item * item)

Good code

items = [1, 3, 5]
other_items = [item * item for item in items]

5. Dictionary comprehension

Bad code

items = [1, 3, 5]
items_dict = {}
for i, item in enumerate(items):
    items_dict[i] = item

Good code

items = [1, 3, 5]
items_dict = {i:item for i, item in enumerate(items)}

6. Use Counter instead of dict for counting elements

Bad code

items = [1, 2, 4, 2, 3, 5, 3, 1, 2, 3, 5, 6, 4]
d = dict()
for item in items:
    if item not in d:
        d[item] = 1
    else:
        d[item] += 1

Good code

from collections import Counter
items = [1, 2, 4, 2, 3, 5, 3, 1, 2, 3, 5, 6, 4]
d = Counter()
for item in items:
    d[item] += 1

Better code

from collections import Counter
items = [1, 2, 4, 2, 3, 5, 3, 1, 2, 3, 5, 6, 4]
d = Counter(items)

7. Use context managers

Bad code

f = open("some_file")
data = f.read()
f.close()

Good code

with open("some_file") as f:
    data = f.read()

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