14 October 2020

Python Data Types and Type Conversion

development

An introduction on Python data types and how to perform type conversions.

Python Data Types

When we create or declare variables in Python, the variables can hold different data types.

Python has the following built-in data types:

str
int, float, complex
list, tuple
dict
set
bool
byte, bytearray

Text Type: str

The str data type is used when we want to declare a string variable.

Example:

x = "some string"
y = str("another string")

Numeric Type: int, float, complex

When we want to create numeric variables we use int, float or complex.

Example:

//int
a = 5
b = int(5)

//float
c = 5.5
d = float(5.5)

//complex
e = 1j
f = complex(1j)

Sequence Type: list, tuple

To create sequence type variables we use list or tuple.

A list is a collection which is ordered and changeable. Allows duplicate members.
A tuple is a collection which is ordered and unchangeable. Allows duplicate members.

Example:

//list
colors = ['red', 'green', 'blue']
colors_list = list(('red', 'green', 'blue'))

//tuple
fruits = ('apple', 'orange', 'banana')
fruits_tuple = list(('apple', 'orange', 'banana'))

Mapping Type: dict

To create a map or dictionary we use dict.

A Dictionary is a collection which is unordered, changeable and indexed. The data are key value pairs.

Example:

people = {"name": "John", "age": "45"}
people_dict = dict(name="John", age=45)

Set Type: set

A set is a collection which is unordered and not indexed.

To create a set, we use set.

Example:

status_codes = {"200", "300", "400", "500"}
status_codes = set(("200", "300", "400", "500"))

Boolean Type: bool

The bool keyword is used to create variables with boolean data type.

is_valid = False
valid = bool(is_valid)

Binary Type: byte, bytearray

Binary data types can be created as follows:

//bytes
a = b"some_text"
b = bytes(5)

//bytearray
c = bytearray(3)

How to get the Type of a Variable

To get the type of a variable we wrap the variable inside the type() function.

For example:

colors = ['red', 'green', 'blue']
colors_list = list(('red', 'green', 'blue'))
print(type(colors_list))
print(colors_list)


fruits = ('apple', 'orange', 'banana')
fruits_tuple = tuple(('apple', 'orange', 'banana'))
print(type(fruits_tuple))
print(fruits_tuple)

Output:

<class 'list'>
['red', 'green', 'blue']
<class 'tuple'>
('apple', 'orange', 'banana')

Python Data Type Conversion

Python defines type conversion functions to directly convert one data type to another, which is quite useful.

Below are some examples:

Convert From int to float

x = 5
y = float(x)
print(y)

Output:

5.0

Convert From float to int

x = 5.0
y = int(x)
print(y)

Output:

Convert From string to list

s = "devqa"
t = list(s)
print(t)

Output:

['d', 'e', 'v', 'q', 'a']

Convert From string to tuple

s = "devqa"
t = tuple(s)
print(t)

Output:

('d', 'e', 'v', 'q', 'a')

Convert From string to set

s = "devqa"
t = set(s)
print(t)

Output:

{'d', 'e', 'a', 'v', 'q'}

14 October 2020