Python Dictionary

# Python Dictionary Examples

# ── Creating dictionaries ─────────────────────────────────────────────────────

empty_dict = {}

person = {"name": "Alice", "age": 30, "city": "New York"}

from_keys = dict(name="Bob", age=25) # using keyword arguments

from_pairs = dict([("a", 1), ("b", 2)]) # from list of tuples

print(person) # {'name': 'Alice', 'age': 30, 'city': 'New York'}

print(from_keys) # {'name': 'Bob', 'age': 25}

print(from_pairs) # {'a': 1, 'b': 2}

# ── Accessing values with keys ────────────────────────────────────────────────

print(person["name"]) # Alice

print(person["age"]) # 30

print(person.get("city")) # New York

print(person.get("email")) # None (no KeyError if key missing)

print(person.get("email", "N/A")) # N/A (default fallback)

# ── Adding / updating / deleting key-value pairs ──────────────────────────────

person["email"] = "alice@example.com" # add new key

# {'name': 'Alice', 'age': 30, 'city': 'New York', 'email': 'alice@example.com'}

person["age"] = 31 # update existing key

# {'name': 'Alice', 'age': 31, 'city': 'New York', 'email': 'alice@example.com'}

del person["city"] # delete a key

# {'name': 'Alice', 'age': 31, 'email': 'alice@example.com'}

removed = person.pop("email") # remove & return value

# removed → 'alice@example.com' | person → {'name': 'Alice', 'age': 31}

person.update({"age": 32, "job": "engineer"}) # add/update multiple keys

# {'name': 'Alice', 'age': 32, 'job': 'engineer'}

# ── Dictionary methods ────────────────────────────────────────────────────────

info = {"name": "Alice", "age": 32, "job": "engineer"}

print(info.keys()) # dict_keys(['name', 'age', 'job'])

print(info.values()) # dict_values(['Alice', 32, 'engineer'])

print(info.items()) # dict_items([('name', 'Alice'), ('age', 32), ('job', 'engineer')])

# Iterating

for key in info.keys():

print(key)

# name

# age

# job

for value in info.values():

print(value)

# Alice

# 32

# engineer

for key, value in info.items():

print(f"{key}: {value}")

# name: Alice

# age: 32

# job: engineer

print("name" in info) # True

print("email" in info) # False

print(len(info)) # 3

info.clear() # info → {}