Dict basics

Learn key-value mapping with {k: v}.

Dict basics

A dict (dictionary) is an ordered collection of key-value pairs. It uses curly braces and a colon:

person = {"name": "Alex", "age": 28}
print(person["name"])  # Alex

A dict maps a key to a value. Keys must be unique; values can be any type. Access is done by key indexing.

Since Python 3.7, a dict keeps its insertion order. This makes loop order stable.

Dict access and assignment

Adding a new key to a dict is done by assignment; querying a missing key raises KeyError:

person = {"name": "Alex"}
person["age"] = 28      # adds a new key
print(person["age"])   # 28
print(person["city"])  # KeyError

To return a default for missing keys, use .get(); this method is safe.

Exercise Print dict elements

Assign the dict {"name": "Ayse", "age": 28} to person. Assign person["name"] to name and person["age"] to age. Then print print(name, age).

Show example solution

person = {"name": "Ayse", "age": 28}
name = person["name"]
age = person["age"]
print(name, age)

Test yourself

Which is a valid dict?
- {"a": 1}
- ("a": 1)
- <"a": 1>
- ["a": 1]
Show answer

{"a": 1} — {"a": 1} with curly braces is a dict.
Match the dict concepts

{"k": v}

Dict syntax
key

Key
value

Value
person["name"]

Access

Access a dict element

person = {"name": "Ayse"}
print(person[____])

Show answer

person = {"name": "Ayse"}
print(person["name"])

Next lesson: Dict methods

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