Advanced comprehensions handle nested data: [item for sub in nested for item in sub] flattens a list. Dict comprehensions transform both keys and values. The walrus := operator assigns inside an expression.
Advanced Comprehensions
# Flatten nested list
nested = [[1,2],[3,4],[5,6]]
flat = [x for sub in nested for x in sub]
# Filter and transform dict
prices = {"apple": 1.5, "banana": 0.5, "cherry": 3.0}
expensive = {k:v for k,v in prices.items() if v > 1.0}
# Walrus operator (Python 3.8+)
if (n := len(expensive)) > 2:
print(f"{n} expensive items")