Lists & loops
Iterate, transform, and combine sequences with readable loop patterns.
How to Flatten One Level of a Nested List in Python
Flattens exactly one level of a nested list by extending the output with each inner list and appending non-list items.
def flatten_one_level(nested_list):
"""Flatten one level of a nested list."""
flattened = []
for item in nested_list:
if isinstance(item, list):
flattened.extend(item)
else:
flattened.append(item)
return flattened
if __name__ == "__main__":
# Example with mi…How to Flatten a Deeply Nested List in Python Recursively
A recursive function that flattens arbitrarily deep nested lists into a single flat list using isinstance checks.
def flatten(nested_list):
if not nested_list:
return []
if isinstance(nested_list[0], list):
return flatten(nested_list[0]) + flatten(nested_list[1:])
return [nested_list[0]] + flatten(nested_list[1:])
if __name__ == "__main__":
data = [1, [2, [3, [4, [5]]]], [6, [7, [8, [9]]]], 10]
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Lists & loops — Python code examples
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