Data Handling
Introduction
Most of the computer programming language support data type, variables,operator and expression like fundamentals.Python also support these.
Data Types
Data Type specifies which type of value a variable can store. type() function is used to determine a variable's type in Python.
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Data Types In Python
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It is used to store numeric values
Python has three numeric types:
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1. Integers
Integers or int are positive or negative numbers with no decimal point. Integers in Python 3 are of unlimited size.
e.g.
a= 100
b= -100
c= 1*20 print(a) print(b) print(c)
Output :-
100
-100
200
Data type continue
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Type Conversion of Integer
int() function converts any data type to integer.
e.g.
a = "101" # string
b=int(a) # converts string data type to integer. c=int(122.4) # converts float data type to integer.
print(b) print(c)Run Code Output :-
101
122
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2. Floating point numbers
It is a positive or negative real numbers with a decimal point.
e.g.
a = 101.2
b = -101.4
c = 111.23 d = 2.3*3
print(a) print(b) print(c)
print(d)Run Code
Output :-
101.2
-101.4
111.23
6.8999999999999995
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3. Complex numbers
Complex numbers are combination of a real and imaginary part.Complex numbers are in the form of X+Yj, where X is a real part and Y is imaginary part.
e.g.
a = complex(5) # convert 5 to a real part val and zero imaginary part
print(a)
b=complex(101,23) #convert 101 with real part and 23 as imaginary part
print(b)Run Code
Output :- (5+0j) (101+23j)
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2. String In Python
Strings:
A string can hold any type of known characters it means letters numbers and special characters of any known scripted language. In python 3.x, each character stored in a string is a Unicode character.
Unicode is a system designed to represent every character from every language.
Following are all legal strings in Python:
“abcd”, “1234”, “$%^&”, ‘????’
Multi line String ”’) Output => Hello World this is
Multi line String
If we print two print Statement Output will be come in two lines
PRINT ( “Hello World”)
PRINT ( “This is me ”) Output => Hello World
This is me
If we want to print in one line we will use
PRINT ( “Hello World”, end=“”)
PRINT ( “This is me ”) Output => Hello WorldThis is me
Or
PRINT ( “Hello World”, end=“ , ”)
PRINT ( “This is me ”) Output => Hello World , This is me
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3. Boolean In Python
Booleans: - these represent the truth values false and true. The Boolean type is subtype of plain integer, and Boolean values false and true behave like 0 and 1, respectively.to get the Boolean equivalent of 0 and 1, you can type bool(0) or bool(1), python will return false or true respectively .
List In Python�
The lists and tuples are Python’s compound data types.
Lists can be changed /modified (it means mutable)
but tuples cannot change or modified (it means immutable).
A list in Python represents a list of comma-separated values of any datatype between square brackets
College= [‘IIT’, ’NIT’, ’College of Engg.’]
Print(College[0]) Output => IIT
Print(College[2]) Output => College of Engg.
College[2]=‘COE’
Print(College[2]) Output => COE
Print(College[1:3]) Output => NIT , COE
College. append(‘Graphic Era’)
Print(College) Output => IIT,NIT,COE , Graphic Era
College. Insert(2, ‘RIE’)
Print(College) Output => IIT,NIT,RIE, COE , Graphic Era
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Tuples are those lists which cannot be changed (it means are not modifiable). Tuples are represented as a list of comma-separated values any data type within parentheses..
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6. Set In Python
It is an unordered collection of unique and immutable (which cannot be modified)items.
e.g.
set1={11,22,33,22}
print(set1)
Output
{33, 11, 22}
Data type continue
7. Dictionary In Python
The dictionary is an unordered set of comma-separated key: value pairs, within { } ,with the requirement that within a dictionary no two keys can be the same
e.g.
name = {'Navneet': 35, 'Gaurav': '42',
‘Sunit’: 36, ‘Vikas’:40}
print(name)
print ("Navneet: ") Output=>> 35
Names[“vikas”]=44
print (“Vikas: ") Output=>> 44
To print only Values
Print(names.values()) Output=>> 35,42,36,40
Print(names.keys()) Output=>> Navneet,,36,40
Input From Keyboard
variable = input(< Prompt to display>)
e.g. name= input(‘What is your name:’)
The input () function always returns a value of string type .
If you enter integer value it will be treated as string .
So we have to convert to desired type int,float.
age= int(input(‘What is your age:’))
type(age) =>> int
Operator
Operators are special symbols in Python that carry out arithmetic or logical computation. The value that the operator operates on is called the operand.
Arithmetic operators
Used for mathematical operation
Operator | Meaning | Example |
+ | Add two operands or unary plus | x + y +2 |
- | Subtract right operand from the left or unary minus | x - y -2 |
* | Multiply two operands | x * y |
/ | Divide left operand by the right one (always results into float) | x / y |
% | Modulus - remainder of the division of left operand by the right | x % y (remainder of x/y) |
// | Floor division - division that results into whole number adjusted to the left in the number line | x // y |
** | Exponent - left operand raised to the power of right | x**y (x to the power y) |
Operator continue
Arithmatic operator continue e.g.
x = 5
y = 4
print('x + y =',x+y) print('x - y =',x-y) print('x * y =',x*y) print('x / y =',x/y) print('x // y =',x//y) print('x ** y =',x**y)
OUTPUT
('x + y =', 9)
('x - y =', 1)
('x * y =', 20)
('x / y =', 1)
('x // y =', 1)
('x ** y =', 625)
Operator continue
Comparison operators
used to compare values
Operator | Meaning | Exampl e |
> | Greater that - True if left operand is greater than the right | x > y |
< | Less that - True if left operand is less than the right | x < y |
== | Equal to - True if both operands are equal | x == y |
!= | Not equal to - True if operands are not equal | x != y |
>= | Greater than or equal to - True if left operand is greater than or equal to the right | x >= y |
<= | Less than or equal to - True if left operand is less than or equal to the right | x <= y |
Operator continue
Comparison operators continue
e.g.
x = 101
y = 121
print('x > y is',x>y) print('x < y is',x<y) print('x == y is',x==y) print('x != y is',x!=y) print('x >= y is',x>=y) print('x <= y is',x<=y)
Output
('x > y is', False)
('x < y is', True)
('x == y is', False)
('x != y is', True)
('x >= y is', False)
('x <= y is', True)
Operator continue
Logical operators
e.g.
x = True y = False
print('x and y is',x and y) print('x or y is',x or y) print('not x is',not x)
Outpur
('x and y is', False)
('x or y is', True)
('not x is', False)
Operator | Meaning | Example |
and | True if both the operands are true | x and y |
or | True if either of the operands is true | x or y |
not | True if operand is false (complements the operand) | not x |
Operator continue
Bitwise operators
Used to manipulate bit values.
Operator | Meaning | Example |
& | Bitwise AND | x& y |
| | Bitwise OR | x | y |
~ | Bitwise NOT | ~x |
^ | Bitwise XOR | x ^ y |
>> | Bitwise right shift | x>> 2 |
<< | Bitwise left shift | x<< 2 |
Operator continue
print ("result of RIGHT SHIFT is ", c,':',bin(c))
Output
('a=', 6, ':', '0b110', 'b=', 3, ':', '0b11')
('result of AND is ', 2, ':', '0b10')
('result of OR is ', 7, ':', '0b111')
('result of EXOR is ', 5, ':', '0b101')
('result of COMPLEMENT is ', -7, ':', '-0b111')
('result of LEFT SHIFT is ', 24, ':', '0b11000')
('result of RIGHT SHIFT is ', 1, ':', '0b1')
Operator continue
Python Membership Operators
Test for membership in a sequence
e.g.
a = 5
b = 10
list = [1, 2, 3, 4, 5 ]
if ( a in list ):
print ("Line 1 - a is available in the given list") else:
print ("Line 1 - a is not available in the given list") if ( b not in list ):
print ("Line 2 - b is not available in the given list") else:
print ("Line 2 - b is available in the given list")
output
Line 1 - a is available in the given list Line 2 - b is not available in the given list
Operator | Description |
in | Evaluates to true if it finds a variable in the specified sequence and false otherwise. |
not in | Evaluates to true if it does not finds a variable in the specified sequence and false otherwise. |
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Python Identity Operators
e.g.
a = 10
b = 10
print ('Line 1','a=',a,':',id(a), 'b=',b,':',id(b)) if ( a is b ):
print ("Line 2 - a and b have same identity") else:
print ("Line 2 - a and b do not have same identity")
OUTPUT
('Line 1', 'a=', 10, ':', 20839436, 'b=', 10, ':', 20839436)
Line 2 - a and b have same identity
Opera tor | Description |
is | Evaluates to true if the variables on either side of the operator point to the same object and false otherwise. |
is not | Evaluates to false if the variables on either side of the operator point to the same object and true otherwise. |
Operator continue
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Operators Precedence :highest precedence to lowest precedence table
Operator | Description |
** | Exponentiation (raise to the power) |
~ + - | Complement, unary plus and minus (method names for the last two are +@ and -@) |
* / % // | Multiply, divide, modulo and floor division |
+ - | Addition and subtraction |
>> << | Right and left bitwise shift |
& | Bitwise 'AND'td> |
^ | | Bitwise exclusive `OR' and regular `OR' |
<= < > >= | Comparison operators |
<> == != | Equality operators |
= %= /= //= -= += *= **= | Assignment operators |
is is not | Identity operators |
in not in | Membership operators |
not or and | Logical operators |
Expression
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It is a valid combination of operators,literals and variable.
Type conversion
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The process of converting the value of one data type (integer, string, float, etc.) to another data type is called type conversion.
Python has two types of type conversion.
Implicit Type Conversion Explicit Type Conversion
Implicit Type Conversion:
In Implicit type conversion, Python automatically converts one data type to another data type. This process doesn't need any user involvement.
e.g.
num_int = 12
num_flo = 10.23
num_new = num_int + num_flo print("datatype of num_int:",type(num_int)) print("datatype of num_flo:",type(num_flo)) print("Value of num_new:",num_new) print("datatype of num_new:",type(num_new))
OUTPUT
('datatype of num_int:', <type 'int'>) ('datatype of num_flo:', <type 'float'>) ('Value of num_new:', 22.23)
('datatype of num_new:', <type 'float'>)
Type conversion
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Explicit Type Conversion:
In Explicit Type Conversion, users convert the data type of an object to required data type. We use the predefined functions like int(),float(),str() etc. e.g.
num_int = 12
num_str = "45"
print("Data type of num_int:",type(num_int))
print("Data type of num_str before Type Casting:",type(num_str)) num_str = int(num_str)
print("Data type of num_str after Type Casting:",type(num_str)) num_sum = num_int + num_str
print("Sum of num_int and num_str:",num_sum) print("Data type of the sum:",type(num_sum))
OUTPUT
('Data type of num_int:', <type 'int'>)
('Data type of num_str before Type Casting:', <type 'str'>) ('Data type of num_str after Type Casting:', <type 'int'>) ('Sum of num_int and num_str:', 57)
('Data type of the sum:', <type 'int'>)
math module
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It is a standard module in Python. To use mathematical functions of this module,we have to import the module using import math.
Function | Description | Example |
ceil(n) | It returns the smallest integer greater than or equal to n. | math.ceil(4.2) returns 5 |
factorial(n) | It returns the factorial of value n | math.factorial(4) returns 24 |
floor(n) | It returns the largest integer less than or equal to n | math.floor(4.2) returns 4 |
fmod(x, y) | It returns the remainder when n is divided by y | math.fmod(10.5,2) returns 0.5 |
exp(n) | It returns e**n | math.exp(1) return 2.718281828459045 |
log2(n) | It returns the base-2 logarithm of n | math.log2(4) return 2.0 |
log10(n) | It returns the base-10 logarithm of n | math.log10(4) returns 0.6020599913279624 |
pow(n, y) | It returns n raised to the power y | math.pow(2,3) returns 8.0 |
sqrt(n) | It returns the square root of n | math.sqrt(100) returns 10.0 |
cos(n) | It returns the cosine of n | math.cos(100) returns 0.8623188722876839 |
sin(n) | It returns the sine of n | math.sin(100) returns -0.5063656411097588 |
tan(n) | It returns the tangent of n | math.tan(100) returns -0.5872139151569291 |
pi | It is pi value (3.14159...) | It is (3.14159...) |
e | It is mathematical constant e (2.71828...) | It is (2.71828...) |