List comprehensions
Python Toolbox
Hugo Bowne-Anderson
Data Scientist at DataCamp
Fyll en lista med en for-loop
nums = [12, 8, 21, 3, 16]new_nums = []for num in nums: new_nums.append(num + 1)print(new_nums)
[13, 9, 22, 4, 17]
En list comprehension
nums = [12, 8, 21, 3, 16] new_nums = [num + 1 for num in nums]print(new_nums)
[13, 9, 22, 4, 17]
Syntax: for-loop och list comprehension
new_nums = [num + 1 for num in nums]
for num in nums: new_nums.append(num + 1)print(new_nums)
[13, 9, 22, 4, 17]
List comprehension med range()
result = [num for num in range(11)]print(result)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
List comprehensions
- Ersätt for-loopar för att bygga listor med en enda rad
- Komponenter
- Iterable
- Iteratorvariabel (representerar element i iterabeln)
- Utdatauttryck
Nästlade loopar (1)
pairs_1 = []for num1 in range(0, 2): for num2 in range(6, 8): pairs_1.append((num1, num2))print(pairs_1)
[(0, 6), (0, 7), (1, 6), (1, 7)]
- Hur gör man detta med en list comprehension?
Nästlade loopar (2)
pairs_2 = [(num1, num2) for num1 in range(0, 2) for num2 in range(6, 8)]print(pairs_2)
[(0, 6), (0, 7), (1, 6), (1, 7)]
- Avvägning: läsbarhet
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