Python Tips
Python Tips
** Special Usages
1. Unpacking a dictionary into keyword arguments in a function call
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def greet(name, age):
print(f"Hello, {name}, You are {age} years old.")
person = {"name": "Alice", "age": 30}
greet(**person)
Output:
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Hello, Alice. You are 30 years old.
2. Merging two dictionaries
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dict1 = {"a": 1, "b": 2}
dict2 = {"b": 3, "c": 4}
merged_dict = {**dict1, **dict2}
print(merged_dict)
Output:
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{'a': 1, 'b': 3, 'c': 4}
Notice that the overlapping key ‘b’, its value is overwritten by
dict2.
* Special Usages
1. Unpacking Iterables
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def add(a, b, c):
return a + b + c
nums = [1, 2, 3]
result = add(*nums)
print(result)
Output:
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6
2. Variable-Length Function Arguments
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def print_all(*args):
for arg in args:
print(arg)
print_all(1, 2, 3, 4)
Output:
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3. Unpacking in Iterables
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a = [1, 2, 3]
b = [*a, 4, 5]
print(b)
Output:
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[1, 2, 3, 4, 5]
4. Keyword-Only Arguments
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def func(a, *, b):
return a + b
# func(1, 2) -> Error, func() takes 1 positional argument but 2 were given
func(1, b=2) # works
5. List/Iterable Multiplication
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repeated = [1, 2, 3] * 3
BTW, be careful when using this syntactic sugar because it may create references to the same object.
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repeated = [[1, 2, 3]] * 3
print(repeated)
repeated[0][0] = 6
print(repeated)
References
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