Chapter 2. covers Data: Types, Values, Variables, and Names

Python basic data types

Name Type Mutable? Examples
Boolean bool no True,False
Interger int no 4,10,78_000
Floating point float no 3.14,0.9,2.7e5
Complex complex no 3j, 5+9j
Text string str no “Humpty Dumpty”, “Jack Sparrow”
List list yes [“Winken”,”Bliken”,”Nod”]
Tuple tuple no (2,4,8)
Bytes bytes no b’ab\xff’
ByteArray bytearray yes bytearray(…)
Set set yes set([3,5,7])
Frozen set frozenset no frozenset({“Elsa,”Otto”})
Dictionary dict yes {“game”:”bingo”,”dog”:”dingo”,”drummer”:”ringo”}

Mutability

mutable = data value contained can be changed immutable = data value is constant(cannot be changed)

Python is strongly typed, which means that the type of an object does not change, even if its value is mutable

Literal values

There are two ways of specifying data values in Python:

Literal

Variable

Variables

Python variable name rules:

  1. can contain only these characters:

  • Lowercase letters (a through z)

  • Uppercase letters (A through Z)

  • Digits (0 through 9)

  • Underscore (_)

  1. case-sensitive: thing, Thing, and THING are different names.

  2. They must begin with a letter or an underscore, not a digit.

  3. Names that begin with an underscore are treated specially

  4. Cannot be one of python’s reserved keywords