1. Data types in python
- What is data type?
- type()
function
- Different
types of data types
- Built-in
data types
- Numeric
types
- int
data type
- float
data type
- complex
data type
- bool
data type (boolean data type)
- None
data type
- Sequences
in Python
- str
data type
- bytes
data type
- bytearray
data type
- list
data structure
- tuple
data structure
- range
data type
- Accessing
range values
- set
data structure
- dictionary
data structure
- User
defined data types
- Converting from one data type into another data type.
- Programs
5. Data types
What is the data type?
- A data type represents the type of data stored into a variable or memory.
Program print different kinds of variables
Name demo1.py
emp_id=1
name=”Nireekshan”
salary=100.50
print(“My employee id is: ”,
emp_id)
print(“My name is: ”, name)
print(“My salary is: ”,
salary)
Output
My employee id is: 1
My name is: Nireekshan
My salary is: 100.5
|
type() function
- type() is an in-built or predefined function in python.
- This is used to check type of the variables
Program print different kinds of variables and
checking their type
Name demo2.py
emp_id=1
name=”Nireekshan”
salary=100.50
print(“My employee id is: ”,
emp_id)
print(“My name is: ”, name)
print(“My salary is: ”,
salary)
print(“emp_id type is: ”,
type(emp_id))
print(“name type is: ”,
type(name))
print(“salary type is: ”,
type(salary))
Output
My employee id is: 1
My name is:
nireekshan
My salary is: 100.5
emp_id type is: <class 'int'>
name type is: <class 'str'>
salary type is: <class 'float'>
|
2 Different types of data types
- There are two type of data types.
- Built-in data types:
- The data types which are already available in python are called built-in data types.
- User-defined data
types:
- Data types which are
created by the programmer.
1.Built-in data types
1.
Numeric types
o int
o float
o complex
2.
bool (boolean type)
3.
None
4.
str
5.
bytes
6.
bytearray
7.
list
8.
set
9.
tuple
10.dict
11.range
1. Numeric types
- The numeric types represent numbers, these are divided into three types,
- int
- float
- complex
1.1 int data type
- The int data type represents values or numbers without decimal values.
- In python there is no limit for the int data type.
- It can store very large values conveniently.
Program To print integer
value
Name demo3.py
a=20
print(a)
print(type(a))
output
20
<class
‘int’>
|
Program To print an integer
value
Name demo4.py
b=9999999999999999999
print(b)
print(type(b))
output
9999999999999999999
<class
‘int’>
|
Info:
- In python 2nd version long data type was existing but in python 3rd version long data type was removed
2. float data type
- The float data type represents a number with a decimal values.
Program To print float value and data type
Name demo5.py
salary = 50.5
print(salary)
print(type(salary))
Output
50.5
<class 'float'>
|
- floating point numbers can also be written in scientific notation.
Program float
values in exponential notation
Name demo6.py
a = 2e2
b = 2E2
c = 2e3
print(a) #
200
print(b) # 200
print(c) # 2000
print(type(a)) #
<class ‘float>
output
200
200
<class
‘float’>
|
- e and E represent exponentiation.
- where e and E to represent the power of 10.
- For example
- The number 2 * 102 is written as 2E2, such numbers are also treated as floating point numbers.
3. complex data type
- The complex data type represents the numbers which is written in the form of,
- a + bj
- a + bJ
- a is representing a real part of number
- b is representing an imaginary part of the number.
- The suffix small j or upper J after b indicates the square root of -1.
- The part ‘a’ and ‘b’ may contain integers or floats.
Program print
complex numbers
Name demo7.py
a = 3+5j
b = 2-5.5j
c = 3+10.5j
print(a)
print(b)
print(c)
print()
print(a+b)
print(b+c)
print(c+a)
output
(3+5j)
(2-5.5j)
(3+10.5j)
(5-0.5j)
(5+5j)
(6+15.5j)
|
Make a note
- If we compare two complex values with <, <=, >, >= operators then we will get TypeError
Program comparing two complex numbers by using > symbol
Name demo8.py
a = 2 + 1j
b = 100 + 10j
print(a>b)
Error
TypeError: '>' not supported between instances of 'complex'
and 'complex'
|
2. bool data type (boolean data type)
- bool data type represents boolean values in python.
- bool data type having only two values those are,
- True
- False
- Python internally represents,
- True as 1(one)
- False as 0(zero)
- An empty string (“ ”) represented as False.
Program printing bool values
Name demo9.py
a = True
b = False
print(a)
print(b)
print(a+a)
print(a+b)
output
True
False
2
1
|
3. None data type
- None data type represents an object that does not contain any value.
- If any object having no value, then we can assign that object with None type.
Program printing None data type
Name demo10.py
a = None
print(a)
print(type(a))
output
None
<class ‘NoneType’>
|
ü If any function is not returning anything then that function can return None data
type.
ü In the below
program, we have created one function and calling that function.
ü If a function can contain a return statement, then that function calling we need to
assign to a variable.
ü This
assigned variable holds return
ü Program 1
ü Program 2
ü We will learn more about this, in the upcoming function chapter.
Program A function return int data type
Name demo11.py
def balance():
print(“This
function returns int data type”)
return 500
b
= balance()
print(b)
Output
This
function returns int data type
500
|
Sequences in Python
ü Sequence means an object can store a group of values,
1.
str
2.
bytes
3.
bytearray
4.
list
5.
tuple
6.
range
1. str data type
ü A group of characters enclosed within single quotes or
double quotes or triple quotes is called as string.
ü We will discuss more about in string chapter.
Program printing string data type
Name demo12.py
name1 = ‘nireekshan’
name2 = “nireekshan”
name3 =
‘’’ nireekshan ‘’’
print(name1)
print(name2)
print(name3)
Output
nireekshan
nireekshan
nireekshan
|
2. bytes data type
ü bytes data type represents group of numbers just like an
array
ü bytes data type can store the values which are from 0 to
256.
ü bytes data type cannot store negative numbers.
create byte data type
o First, we need to create list.
o The created list we need to pass to bytes() function as a parameter
ü bytes data type is immutable means we cannot modify or change the bytes object.
Program Creating bytes data type
Name demo14.py
x = [10, 20, 100, 40, 15]
y
= bytes(x)
print(type(y))
Output
<class 'bytes'>
|
Program accessing bytes data type elements by using index
Name demo15.py
x = [10, 20, 30, 40, 15]
y
= bytes(x)
print(y[0])
print(y[1])
print(y[2])
print(y[3])
print(y[4])
Output
10
20
30
40
15
|
ü We can iterate bytes values by using for loop.
Program printing values from bytes data type
Name demo16.py
x = [10, 20, 100, 40, 15]
y
= bytes(x)
for a in y:
print(a)
output
10
20
100
40
15
|
Program ValueError: bytes must be in range(0, 256)
Name demo17.py
x = [10, 20, 300, 40, 15]
y
= bytes(x)
Error
ValueError: bytes must be in range(0, 256)
|
Program bytes data type is immutable
Name demo18.py
x = [10, 20, 30, 40, 15]
y
= bytes(x)
y[0]
= 30
Error
TypeError: 'bytes' object does not support item assignment
|
3. bytearray data type
ü bytearray is same as bytes data type, but bytearray is mutable means we can modify the content of bytearray data type.
creating bytearray type
o First, we need to create list.
o The created list we need to pass as bytearray()
parameter
Program creating bytearray data type
Name demo19.py
x = [10, 20, 30, 40, 15]
y
= bytearray(x)
print(type(y))
Output
<class 'bytearray'>
|
Program accessing bytes data type elements by using index
Name demo20.py
x = [10, 20, 30, 40, 15]
y = bytearray(x)
print(y[0])
print(y[1])
print(y[2])
print(y[3])
print(y[4])
Output
10
20
30
40
15
|
ü We can iterate bytearray values by using for loop.
Program printing values from bytearray data type by using for
loop
Name demo21.py
x = [10, 20, 30, 40, 15]
y
= bytearray(x)
for a in y:
print(a)
Output
10
20
30
40
15
|
Program bytearray data type is mutable
Name demo22.py
x = [10, 20, 30, 40, 15]
y
= bytearray(x)
print("Before modifying y[0] value: ", y[0])
y[0] = 30
print("After modifying y[0] value: ", y[0])
Output
before modifying y[0] value: 10
after modifying y[0] value: 30
|
4. list data structure
ü We can create list data structure by using square
brackets []
ü list can store different data types
ü list is mutable.
ü We will discuss more about in list chapter.
5. tuple data structure
ü We can create tuple data structure by using parenthesis ()
ü tuple can store different data types.
ü tuple is immutable.
ü We will discuss more about in tuple chapter.
6. range data type
ü We can create a range
of values by using range() function
ü The range datatype
represents a sequence of numbers.
ü range data type is
immutable, means we cannot modify once it created.
ü range data type
values can be print by using for loop.
Program creating
a range of values 0 to 4 by using range() function
Name demo23.py
a=range(5)
print(a)
for x
in a:
print(x)
Output
range(0, 5)
0
1
2
3
4
|
Make a note
ü We can create a list of values with range data type
Program Creating list of values
Name demo24.py
a=list(range(1, 10))
print(a)
Output
[1, 2, 3, 4, 5, 6, 7, 8, 9]
|
Accessing range values
ü By using index, we can access elements present in the
range data type
Program Access elements from range data type
Name demo25.py
a=range(1, 10)
print(a[0])
print(a[1])
output
1
2
|
ü If we are trying to access range data type values in out
of range then we will get error.
Program Access elements from range data type
Name demo26.py
a=range(1, 10)
print(a[0])
print(a[20])
Error
IndexError:
range object index out of range
|
7. set data structure
ü We can create set data structure by using parenthesis
symbols {}
ü set can store same type and different type of elements
ü We will learn more in set chapter
8. dictionary data structure
ü We can create dictionary type by using curly braces {}
ü dict represents group of elements in the form of key value pairs like map.
ü We will discuss more in dict chapter
User defined data types
ü The datatype which are created by the programmers are
called ‘user-defined’ datatypes, example is class, module, array etc
ü We will discuss about in OOPS upcoming chapter.
Make a note
ü In Python the
following data types are considered as Fundamental Data types,
o
int
o
float
o
complex
o
bool
o
str
Converting from one data type into another data type.
ü Based on requirement developer can convert from one data
type into another data type explicitly, this is called type conversion.
ü Python provides in build functions to convert from one
type to another type.
o int() : convert from other type into int type
o float() : convert from other type into float type
o complex() : convert from other type into complex
type
o bool() : convert from other type into bool type
o str() : convert from other type into str type