Set and Dict Comprehensions

Introduction

Set Comprehension Syntax

unique_lens = {len(w) for w in ['apple','banana','fig']}
print(unique_lens)

Deduplication with Set Comprehension

mods = {x % 3 for x in range(9)}
print(mods)

Set Comprehension with Condition

print({x for x in range(20) if x%2==0 and x%3==0})

Dict Comprehension Syntax

squares = {x: x**2 for x in range(5)}
print(squares)

Dict Comprehension with Condition

d = {'a': 1, 'b': -2, 'c': 3}
pos = {k: v for k, v in d.items() if v > 0}
print(pos)

Inverting a Dict

d = {'a': 1, 'b': 2, 'c': 3}
print({v: k for k, v in d.items()})

Grouping with Dict Comprehension

words = ['apple','ant','banana','cherry','cat']
grouped = {l: [w for w in words if w.startswith(l)] for l in 'abc'}
print(grouped)

Combining Two Lists into a Dict

keys = ['x', 'y', 'z']
vals = [1, 4, 9]
print({k: v**0.5 for k, v in zip(keys, vals)})

Nested Dict Comprehension

table = {i: {j: i*j for j in range(3)} for i in range(3)}
print(table)

When to Use Each

words = ['hello', 'world', 'hello']
unique = {w for w in words}
lengths = {w: len(w) for w in unique}
print(lengths)

Quick Check

Recap

Keep Going