Source: 11 Tips And Tricks To Write Better Python Code
1. Iterate with enumerate instead of range(len(x))
1
2
3
4
5
6
| data = [1, 2, -4 , -3]
for i, num in enumerate(data):
if num < 0:
data[i] = 0
print(data)
# [1, 2, 0, 0]
|
2. Use list comprehension instead of raw for loop
1
| squares = [i*i for i in range(10)]
|
3. Sort complex iterables with sorted()
List
1
2
3
4
| data = [3, 5, 1, 10, 9]
sorted_data = sorted(data, reverse=True)
print(sorted_data)
# [10, 9, 5, 3, 1]
|
Dictionary
1
2
3
4
5
6
7
8
| data = [ {"name": "Max", "age": 6},
{"name": "Lisa", "age": 20},
{"name": "Ben", "age": 9},]
sorted_data = sorted(data, key=lambda x: x["age"])
# key is a function
print(sorted_data)
# [{"name": "Max", "age": 6}, {"name": "Ben", "age": 9}, {"name": "Lisa", "age": 20}]
|
4. Store unique values with Sets
A set is an unordered collection data type with no duplicate elements.
1
2
3
4
| my_list = {1, 3, 4, 5, 6, 7, 7, 7}
my_set = set(my_list)
print(my_set)
# {1, 2, 3, 4, 5, 6, 7}
|
5. Save memory with generators
Generator computes elements lazily, producing one element at a time and only when asked for it
1
2
3
4
5
6
7
8
9
10
11
12
| import sys
my_list = [i for i in range(10000)]
print(sum(my_list))
# 49995000
print(sys.getsizeof(my_list), "bytes")
# 87632 bytes
my_gen = (i for i in range(10000))
print(sum(my_gen))
# 49995000
print(sys.getsizeof(my_gen), "bytes")
# 128 bytes
|
6. Define default values in Dictionaries with .get() and .setdefault()
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
| my_dict = {"item": "football", "price": 10.00}
count = my_dict["count"]
# KeyError: 'count'
count = my_dict.get("count")
print(count)
# None
# with default value
count = my_dict.get("count", 0)
print(count)
# 0
count = my_dict.setdefault("count", 0)
print(count)
# 0
print(my_dict)
# {"item": "football", "price": 10.00, "count": 0}
|
7. Count hashable objects with collections.Counter
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
| from collections import Counter
my_list = [10, 10, 10, 5, 5, 2, 9, 9, 9, 9, 9, 9]
counter = Counter(my_list)
print(counter)
# Counter({9:6, 10: 3, 5:2, 2: 1})
print(counter[10])
# 3
print(counter[11])
# 0
most_common = counter.most_common(1)
print(most_common)
# [(9, 6)]
most_common = counter.most_common(2)
print(most_common)
# [(10, 3)]
|
1
2
3
4
5
6
7
| name = "Alex"
my_string = f"Hello {name}"
print(my_string)
# with experssions
i = 10
print(f"{i} squared is {i+1}")
|
9. Concatenate strings with .join
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
| list_of_strings = ["Hello", "my", "friend"]
# BAD!
my_string = ""
for i in list_of_strings:
my_string += i + " "
# string is immutable so we're creating a new string everytime
# and will be slow for large lists
print(my_string)
# Hello my friend
# GOOD
my_string = " ".join(list_of_strings)
print(my_string)
# Hello my friend
|
10. Merge dictionaries with {**d1, **d2} (3.5+)
1
2
3
4
5
| d1 = {"name": "Alex", "age": 25}
d2 = {"name": "Alex", "city": "New York"}
merged_dict = {**d1,**d2}
print(merged_dict)
# {"name": "Alex", "age": 25, "city": "New York"}
|
11. Simplify if-statement with if x in [a, b, c]
instead of checking each item separately
1
2
3
4
5
| colors = ["red", "green", "blue"]
c = "red"
if c in colors:
print("is a main color")
|