Python Built-in Functions
The Python built-in functions are defined as the functions whose functionality is pre-defined in Python. The python interpreter has several functions that are always present for use.
abs()
The python abs() function is used to return the absolute value of a number. It takes only one argument, a number whose absolute value is to be returned. The argument can be an integer and floating-point number. If the argument is a complex number, then, abs() returns its magnitude.
Example:
# integer number
integer = -20
print('Absolute value of -40 is:', abs(integer))
# floating number
floating = -20.83
print('Absolute value of -40.83 is:', abs(floating))
Output:
Absolute value of -20 is: 20
Absolute value of -20.83 is: 20.83
all()
The python all() function accepts an iterable object (such as list, dictionary, etc.). It returns true if all items in passed iterable are true. Otherwise, it returns False. If the iterable object is empty, the all() function returns True.
Example:
# all values true
k = [1, 3, 4, 6]
print(all(k))
# all values false
k = [0, False]
print(all(k))
# one false value
k = [1, 3, 7, 0]
print(all(k))
# one true value
k = [0, False, 5]
print(all(k))
# empty iterable
k = []
print(all(k))
Output:
True
False
False
False
True
bin()
The python bin() function is used to return the binary representation of a specified integer. A result always starts with the prefix 0b.
Example:
x = 10
y = bin(x)
print (y)
Output:
0b1010
bool()
The python bool() converts a value to boolean(True or False) using the standard truth testing procedure.
Example:
test1 = []
print(test1,'is',bool(test1))
test1 = [0]
print(test1,'is',bool(test1))
test1 = 0.0
print(test1,'is',bool(test1))
test1 = None
print(test1,'is',bool(test1))
test1 = True
print(test1,'is',bool(test1))
test1 = 'Easy string'
print(test1,'is',bool(test1))
Output:
[] is False
[0] is True
0.0 is False
None is False
True is True
Easy string is True
bytes()
The python bytes() in Python is used for returning a bytes object. It is an immutable version of the bytearray() function.
It can create empty bytes object of the specified size.
Example:
string = "Hello World."
array = bytes(string, 'utf-8')
print(array)
Output:
b ' Hello World.'
callable()
A python callable() function in Python is something that can be called. This built-in function checks and returns true if the object passed appears to be callable, otherwise false.
Example:
x = 8
print(callable(x))
Output:
False
compile()
The python compile() function takes source code as input and returns a code object which can later be executed by exec() function.
Example:
# compile string source to code
code_str = 'x=5\ny=10\nprint("sum =",x+y)'
code = compile(code_str, 'sum.py', 'exec')
print(type(code))
exec(code)
exec(x)
Output:
<class 'code'>
sum = 15
exec()
The python exec() function is used for the dynamic execution of Python program which can either be a string or object code and it accepts large blocks of code, unlike the eval() function which only accepts a single expression.
Example:
x = 8
exec('print(x==8)')
exec('print(x+4)')
Output:
True
12
sum()
As the name says, python sum() function is used to get the sum of numbers of an iterable, i.e., list.
Example:
s = sum([1, 2,4 ])
print(s)
s = sum([1, 2, 4], 10)
print(s)
Output:
7
17
any()
The python any() function returns true if any item in an iterable is true. Otherwise, it returns False.
Example:
l = [4, 3, 2, 0]
print(any(l))
l = [0, False]
print(any(l))
l = [0, False, 5]
print(any(l))
l = []
print(any(l))
Output:
True
False
True
False
ascii()
The python ascii() function returns a string containing a printable representation of an object and escapes the non-ASCII characters in the string using \x, \u or \U escapes.
Example:
normalText = 'Python is interesting'
print(ascii(normalText))
otherText = 'Pythön is interesting'
print(ascii(otherText))
print('Pyth\xf6n is interesting')
Output:
'Python is interesting'
'Pyth\xf6n is interesting'
Pythön is interesting
bytearray()
The python bytearray() returns a bytearray object and can convert objects into bytearray objects, or create an empty bytearray object of the specified size.
Example:
string = "Python is a programming language."
# string with encoding 'utf-8'
arr = bytearray(string, 'utf-8')
print(arr)
Output:
bytearray(b'Python is a programming language.')
eval()
The python eval() function parses the expression passed to it and runs python expression(code) within the program.
Example:
x = 8
print(eval('x + 1'))
Output:
9
float()
The python float() function returns a floating-point number from a number or string.
Example:
# for integers
print(float(9))
# for floats
print(float(8.19))
# for string floats
print(float("-24.27"))
# for string floats with whitespaces
print(float(" -17.19\n"))
# string float error
print(float("xyz"))
Output:
9.0
8.19
-24.27
-17.19
ValueError: could not convert string to float: 'xyz'
format()
The python format() function returns a formatted representation of the given value.
Example:
# d, f and b are a type
# integer
print(format(123, "d"))
# float arguments
print(format(123.4567898, "f"))
# binary format
print(format(12, "b"))
Output:
123
123.456790
1100
frozenset()
The python frozenset() function returns an immutable frozenset object initialized with elements from the given iterable.
Example:
# tuple of letters
letters = ('m', 'r', 'o', 't', 's')
fSet = frozenset(letters)
print('Frozen set is:', fSet)
print('Empty frozen set is:', frozenset())
Output:
Frozen set is: frozenset({'o', 'm', 's', 'r', 't'})
Empty frozen set is: frozenset()
getattr()
The python getattr() function returns the value of a named attribute of an object. If it is not found, it returns the default value.
Example:
class Details:
age = 22
name = "Phill"
details = Details()
print('The age is:', getattr(details, "age"))
print('The age is:', details.age)
Output:
The age is: 22
The age is: 22
globals()
The python globals() function returns the dictionary of the current global symbol table.
A Symbol table is defined as a data structure which contains all the necessary information about the program. It includes variable names, methods, classes, etc.
Example:
age = 22
globals()['age'] = 22
print('The age is:', age)
Output:
The age is: 22
hasattr()
The python any() function returns true if any item in an iterable is true, otherwise it returns False.
Example:
l = [4, 3, 2, 0]
print(any(l))
l = [0, False]
print(any(l))
l = [0, False, 5]
print(any(l))
l = []
print(any(l))
Output:
True
False
True
False
iter()
The python iter() function is used to return an iterator object. It creates an object which can be iterated one element at a time.
Example:
# list of numbers
list = [1,2,3,4,5]
listIter = iter(list)
# prints '1'
print(next(listIter))
# prints '2'
print(next(listIter))
# prints '3'
print(next(listIter))
# prints '4'
print(next(listIter))
# prints '5'
print(next(listIter))
Output:
1
2
3
4
5
len()
The python len() function is used to return the length (the number of items) of an object.
Example:
strA = 'Python'
print(len(strA))
Output:
6
list()
The python list() creates a list in python.
Example:
# empty list
print(list())
# string
String = 'abcde'
print(list(String))
# tuple
Tuple = (1,2,3,4,5)
print(list(Tuple))
# list
List = [1,2,3,4,5]
print(list(List))
Output:
[]
['a', 'b', 'c', 'd', 'e']
[1,2,3,4,5]
[1,2,3,4,5]
locals()
The python locals() method updates and returns the dictionary of the current local symbol table.
A Symbol table is defined as a data structure which contains all the necessary information about the program. It includes variable names, methods, classes, etc.
Example:
def localsAbsent():
return locals()
def localsPresent():
present = True
return locals()
print('localsNotPresent:', localsAbsent())
print('localsPresent:', localsPresent())
Output:
localsAbsent: {}
localsPresent: {'present': True}
map()
The python map() function is used to return a list of results after applying a given function to each item of an iterable(list, tuple etc.).
Example:
def calculateAddition(n):
return n+n
numbers = (1, 2, 3, 4)
result = map(calculateAddition, numbers)
print(result)
# converting map object to set
numbersAddition = set(result)
print(numbersAddition)
Output:
<map object at 0x7fb04a6bec18>
{8, 2, 4, 6}
memoryview()
The python memoryview() function returns a memoryview object of the given argument.
Example:
#A random bytearray
randomByteArray = bytearray('ABC', 'utf-8')
mv = memoryview(randomByteArray)
# access the memory view's zeroth index
print(mv[0])
# It create byte from memory view
print(bytes(mv[0:2]))
# It create list from memory view
print(list(mv[0:3]))
Output:
65
b'AB'
[65, 66, 67]
object()
The python object() returns an empty object. It is a base for all the classes and holds the built-in properties and methods which are default for all the classes.
Example:
python = object()
print(type(python))
print(dir(python))
Output:
<class 'object'>
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__',
'__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__ne__',
'__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',
'__str__', '__subclasshook__']
open()
The python open() function opens the file and returns a corresponding file object.
Example:
# opens python.text file of the current directory
f = open("python.txt")
# specifying full path
f = open("C:/Python33/README.txt")
Output:
Since the mode is omitted, the file is opened in 'r' mode; opens for reading.
chr()
Python chr() function is used to get a string representing a character which points to a Unicode code integer. For example, chr(97) returns the string ‘a’. This function takes an integer argument and throws an error if it exceeds the specified range. The standard range of the argument is from 0 to 1,114,111.
Example:
# Calling function
result = chr(102) # It returns string representation of a char
result2 = chr(112)
# Displaying result
print(result)
print(result2)
# Verify, is it string type?
print("is it string type:", type(result) is str)
Output:
ValueError: chr() arg not in range(0x110000)
complex()
Python complex() function is used to convert numbers or string into a complex number. This method takes two optional parameters and returns a complex number. The first parameter is called a real and second as imaginary parts.
Example:
# Python complex() function example
# Calling function
a = complex(1) # Passing single parameter
b = complex(1,2) # Passing both parameters
# Displaying result
print(a)
print(b)
Output:
(1.5+0j)
(1.5+2.2j)
delattr()
Python delattr() function is used to delete an attribute from a class. It takes two parameters, first is an object of the class and second is an attribute which we want to delete. After deleting the attribute, it no longer available in the class and throws an error if try to call it using the class object.
Example:
class Student:
id = 101
name = "Pranshu"
email = "pranshu@abc.com"
# Declaring function
def getinfo(self):
print(self.id, self.name, self.email)
s = Student()
s.getinfo()
delattr(Student,'course') # Removing attribute which is not available
s.getinfo() # error: throws an error
Output:
101 Pranshu pranshu@abc.com
AttributeError: course
dir()
Python dir() function returns the list of names in the current local scope. If the object on which method is called has a method named dir(), this method will be called and must return the list of attributes. It takes a single object type argument.
Example:
# Calling function
att = dir()
# Displaying result
print(att)
Output:
['__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__',
'__name__', '__package__', '__spec__']
divmod()
Python divmod() function is used to get remainder and quotient of two numbers. This function takes two numeric arguments and returns a tuple. Both arguments are required and numeric
Example:
# Python divmod() function example
# Calling function
result = divmod(10,2)
# Displaying result
print(result)
Output:
(5, 0)
enumerate()
Python enumerate() function returns an enumerated object. It takes two parameters, first is a sequence of elements and the second is the start index of the sequence. We can get the elements in sequence either through a loop or next() method.
Example:
# Calling function
result = enumerate([1,2,3])
# Displaying result
print(result)
print(list(result))
Output:
<enumerate object at 0x7ff641093d80>
[(0, 1), (1, 2), (2, 3)]
dict()
Python dict() function is a constructor which creates a dictionary. Python dictionary provides three different constructors to create a dictionary:
- If no argument is passed, it creates an empty dictionary.
- If a positional argument is given, a dictionary is created with the same key-value pairs. Otherwise, pass an iterable object.
- If keyword arguments are given, the keyword arguments and their values are added to the dictionary created from the positional argument.
Example:
# Calling function
result = dict() # returns an empty dictionary
result2 = dict(a=1,b=2)
# Displaying result
print(result)
print(result2)
Output:
{}
{'a': 1, 'b': 2}
filter()
Python filter() function is used to get filtered elements. This function takes two arguments, first is a function and the second is iterable. The filter function returns a sequence of those elements of iterable object for which function returns true value.
The first argument can be none, if the function is not available and returns only elements that are true.
Example:
# Python filter() function example
def filterdata(x):
if x>5:
return x
# Calling function
result = filter(filterdata,(1,2,6))
# Displaying result
print(list(result))
Output:
[6]
hash()
Python hash() function is used to get the hash value of an object. Python calculates the hash value by using the hash algorithm. The hash values are integers and used to compare dictionary keys during a dictionary lookup. We can hash only the types which are given below:
Hashable types: * bool * int * long * float * string * Unicode * tuple * code object.
Example:
# Calling function
result = hash(21) # integer value
result2 = hash(22.2) # decimal value
# Displaying result
print(result)
print(result2)
Output:
21
461168601842737174
help()
Python help() function is used to get help related to the object passed during the call. It takes an optional parameter and returns help information. If no argument is given, it shows the Python help console. It internally calls python’s help function.
Example:
# Calling function
info = help() # No argument
# Displaying result
print(info)
Output:
Welcome to Python 3.5's help utility!
min()
Python min() function is used to get the smallest element from the collection. This function takes two arguments, first is a collection of elements and second is key, and returns the smallest element from the collection.
Example:
# Calling function
small = min(2225,325,2025) # returns smallest element
small2 = min(1000.25,2025.35,5625.36,10052.50)
# Displaying result
print(small)
print(small2)
Output:
325
1000.25
set()
In python, a set is a built-in class, and this function is a constructor of this class. It is used to create a new set using elements passed during the call. It takes an iterable object as an argument and returns a new set object.
Example:
# Calling function
result = set() # empty set
result2 = set('12')
result3 = set('javatpoint')
# Displaying result
print(result)
print(result2)
print(result3)
Output:
set()
{'1', '2'}
{'a', 'n', 'v', 't', 'j', 'p', 'i', 'o'}
hex()
Python hex() function is used to generate hex value of an integer argument. It takes an integer argument and returns an integer converted into a hexadecimal string. In case, we want to get a hexadecimal value of a float, then use float.hex() function.
Example:
# Calling function
result = hex(1)
# integer value
result2 = hex(342)
# Displaying result
print(result)
print(result2)
Output:
0x1
0x156
id()
Python id() function returns the identity of an object. This is an integer which is guaranteed to be unique. This function takes an argument as an object and returns a unique integer number which represents identity. Two objects with non-overlapping lifetimes may have the same id() value.
Example:
# Calling function
val = id("Javatpoint") # string object
val2 = id(1200) # integer object
val3 = id([25,336,95,236,92,3225]) # List object
# Displaying result
print(val)
print(val2)
print(val3)
Output:
139963782059696
139963805666864
139963781994504
setattr()
Python setattr() function is used to set a value to the object’s attribute. It takes three arguments, i.e., an object, a string, and an arbitrary value, and returns none. It is helpful when we want to add a new attribute to an object and set a value to it.
Example:
class Student:
id = 0
name = ""
def __init__(self, id, name):
self.id = id
self.name = name
student = Student(102,"Sohan")
print(student.id)
print(student.name)
#print(student.email) product error
setattr(student, 'email','sohan@abc.com') # adding new attribute
print(student.email)
Output:
102
Sohan
sohan@abc.com
slice()
Python slice() function is used to get a slice of elements from the collection of elements. Python provides two overloaded slice functions. The first function takes a single argument while the second function takes three arguments and returns a slice object. This slice object can be used to get a subsection of the collection.
Example:
# Calling function
result = slice(5) # returns slice object
result2 = slice(0,5,3) # returns slice object
# Displaying result
print(result)
print(result2)
Output:
slice(None, 5, None)
slice(0, 5, 3)
sorted()
Python sorted() function is used to sort elements. By default, it sorts elements in an ascending order but can be sorted in descending also. It takes four arguments and returns a collection in sorted order. In the case of a dictionary, it sorts only keys, not values.
Example:
str = "javatpoint" # declaring string
# Calling function
sorted1 = sorted(str) # sorting string
# Displaying result
print(sorted1)
Output:
['a', 'a', 'i', 'j', 'n', 'o', 'p', 't', 't', 'v']
next()
Python next() function is used to fetch next item from the collection. It takes two arguments, i.e., an iterator and a default value, and returns an element.
This method calls on iterator and throws an error if no item is present. To avoid the error, we can set a default value.
Example:
number = iter([256, 32, 82]) # Creating iterator
# Calling function
item = next(number)
# Displaying result
print(item)
# second item
item = next(number)
print(item)
# third item
item = next(number)
print(item)
Output:
256
32
82
input()
Python input() function is used to get an input from the user. It prompts for the user input and reads a line. After reading data, it converts it into a string and returns it. It throws an error EOFError if EOF is read.
Example:
# Calling function
val = input("Enter a value: ")
# Displaying result
print("You entered:",val)
Output:
Enter a value: 45
You entered: 45
int()
Python int() function is used to get an integer value. It returns an expression converted into an integer number. If the argument is a floating-point, the conversion truncates the number. If the argument is outside the integer range, then it converts the number into a long type.
If the number is not a number or if a base is given, the number must be a string.
Example:
# Calling function
val = int(10) # integer value
val2 = int(10.52) # float value
val3 = int('10') # string value
# Displaying result
print("integer values :",val, val2, val3)
Output:
integer values : 10 10 10
isinstance()
Python isinstance() function is used to check whether the given object is an instance of that class. If the object belongs to the class, it returns true. Otherwise returns False. It also returns true if the class is a subclass.
The isinstance() function takes two arguments, i.e., object and classinfo, and then it returns either True or False.
Example:
class Student:
id = 101
name = "John"
def __init__(self, id, name):
self.id=id
self.name=name
student = Student(1010,"John")
lst = [12,34,5,6,767]
# Calling function
print(isinstance(student, Student)) # isinstance of Student class
print(isinstance(lst, Student))
Output:
True
False
oct()
Python oct() function is used to get an octal value of an integer number. This method takes an argument and returns an integer converted into an octal string. It throws an error TypeError, if argument type is other than an integer.
Example:
# Calling function
val = oct(10)
# Displaying result
print("Octal value of 10:",val)
Output:
Octal value of 10: 0o12
ord()
The python ord() function returns an integer representing Unicode code point for the given Unicode character.
Example:
# Code point of an integer
print(ord('8'))
# Code point of an alphabet
print(ord('R'))
# Code point of a character
print(ord('&'))
Output:
56
82
38
pow()
The python pow() function is used to compute the power of a number. It returns x to the power of y. If the third argument(z) is given, it returns x to the power of y modulus z, i.e. (x, y) % z.
Example:
# positive x, positive y (x**y)
print(pow(4, 2))
# negative x, positive y
print(pow(-4, 2))
# positive x, negative y (x**-y)
print(pow(4, -2))
# negative x, negative y
print(pow(-4, -2))
Output:
16
16
0.0625
0.0625
print()
The python print() function prints the given object to the screen or other standard output devices.
Example:
print("Python is programming language.")
x = 7
# Two objects passed
print("x =", x)
y = x
# Three objects passed
print('x =', x, '= y')
Output:
Python is programming language.
x = 7
x = 7 = y
range()
The python range() function returns an immutable sequence of numbers starting from 0 by default, increments by 1 (by default) and ends at a specified number.
Example:
# empty range
print(list(range(0)))
# using the range(stop)
print(list(range(4)))
# using the range(start, stop)
print(list(range(1,7 )))
Output:
[]
[0, 1, 2, 3]
[1, 2, 3, 4, 5, 6]
reversed()
The python reversed() function returns the reversed iterator of the given sequence.
Example:
# for string
String = 'Java'
print(list(reversed(String)))
# for tuple
Tuple = ('J', 'a', 'v', 'a')
print(list(reversed(Tuple)))
# for range
Range = range(8, 12)
print(list(reversed(Range)))
# for list
List = [1, 2, 7, 5]
print(list(reversed(List)))
Output:
['a', 'v', 'a', 'J']
['a', 'v', 'a', 'J']
[11, 10, 9, 8]
[5, 7, 2, 1]
round()
The python round() function rounds off the digits of a number and returns the floating point number.
Example:
# for integers
print(round(10))
# for floating point
print(round(10.8))
# even choice
print(round(6.6))
Output:
10
11
7
issubclass()
The python issubclass() function returns true if object argument(first argument) is a subclass of second class(second argument).
Example:
class Rectangle:
def __init__(rectangleType):
print('Rectangle is a ', rectangleType)
class Square(Rectangle):
def __init__(self):
Rectangle.__init__('square')
print(issubclass(Square, Rectangle))
print(issubclass(Square, list))
print(issubclass(Square, (list, Rectangle)))
print(issubclass(Rectangle, (list, Rectangle)))
Output:
True
False
True
True
str()
The python str() converts a specified value into a string.
Example:
str('4')
Output:
'4'
tuple()
The python tuple() function is used to create a tuple object.
Example:
t1 = tuple()
print('t1=', t1)
# creating a tuple from a list
t2 = tuple([1, 6, 9])
print('t2=', t2)
# creating a tuple from a string
t1 = tuple('Java')
print('t1=',t1)
# creating a tuple from a dictionary
t1 = tuple({4: 'four', 5: 'five'})
print('t1=',t1)
Output:
t1= ()
t2= (1, 6, 9)
t1= ('J', 'a', 'v', 'a')
t1= (4, 5)
type()
The python type() returns the type of the specified object if a single argument is passed to the type() built in function. If three arguments are passed, then it returns a new type object.
Example:
List = [4, 5]
print(type(List))
Dict = {4: 'four', 5: 'five'}
print(type(Dict))
class Python:
a = 0
InstanceOfPython = Python()
print(type(InstanceOfPython))
Output:
<class 'list'>
<class 'dict'>
<class '__main__.Python'>
vars()
The python vars() function returns the dict attribute of the given object.
Example:
class Python:
def __init__(self, x = 7, y = 9):
self.x = x
self.y = y
InstanceOfPython = Python()
print(vars(InstanceOfPython))
Output:
{'y': 9, 'x': 7}
zip()
The python zip() Function returns a zip object, which maps a similar index of multiple containers. It takes iterables (can be zero or more), makes it an iterator that aggregates the elements based on iterables passed, and returns an iterator of tuples.
Example:
numList = [4,5, 6]
strList = ['four', 'five', 'six']
# No iterables are passed
result = zip()
# Converting itertor to list
resultList = list(result)
print(resultList)
# Two iterables are passed
result = zip(numList, strList)
# Converting itertor to set
resultSet = set(result)
print(resultSet)
Output:
[]
{(5, 'five'), (4, 'four'), (6, 'six')}