Built-in functions in python
We have already discussed about Function in Python i.e. user defined functions. In this we are studying built-in functions in python.
Python consists of various function whose functioning is predefined in python itself.
Such functions are called as built-in functions.
There are 68 built-in functions present in python.
List of few of built-in functions
List of few of built-in functions and its description are as follows :
abs()
It is one of the python built-in functions which returns absolute value of a number. A negative digit is turned to positive.
Example
>>> a=-9 >>> abs(a) 9 >>> abs(0) 0 >>> abs(9) 9 >>> >>> abs(-4.2) 4.2
all()
The all() function takes a container as an argument. This built-in function returns True if all values in a python iterable have a Boolean value of True. An empty value has a Boolean value of False.
Example
>>> all(['','','']) False >>> all([' ',' ',' ']) True >>> all([1,2,6]) True
any()
The any() function takes a container as an argument. This built-in function returns True if any one values in a python iterable have a Boolean value of True. An empty value has a Boolean value of False.
Example
>>> any(['','','']) False >>> any([' ',' ',' ']) True >>> any([1,0,0]) True >>> any([0,0,0]) False
bin()
The bin() built-in functions returns the binary representation of an integer.
Example
>>> bin(10) '0b1010' >>> bin(7) '0b111' >>>
Note: The output of bin() has ‘0b’ in beginning which indicates that it is a binary number.
bool()
The bool() returns True when the argument x is True, False otherwise. The builtins True and False are the only two instances of the class bool.
Example
>>> bool(0)
False
>>> bool(5)
True
>>> bool('')
False
>>> bool(' ')
True
chr()
The chr(i) return a Unicode string of one character with ordinal i
Example
>>> chr(97) 'a' >>> chr(65) 'A' >>> chr(92) '' >>>
dict()
The dict() function is use to create a dictionary having key and value pairs.
It creates empty dictionary if no parameters are passed.
Example
>>> dict([(1,2),(3,4),(5,6),(7,8),(9,10)])
{1: 2, 3: 4, 9: 10, 5: 6, 7: 8}
>>> dict()
{}
>>>
dir()
The dir() function returns list of strings comprising of the attributes of the given objects. If called without an argument it returns the name with the current scope.
Example
>>> dir() ['__builtins__', '__doc__', '__loader__', '__name__', '__package__', '__spec__'] >>> dir(list) ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', >>> dir(str) ['__add__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'capitalize', 'casefold', 'center', 'count', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 'isalnum', 'isalpha', 'isascii', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans', 'partition', 'removeprefix', 'removesuffix', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']
divmod()
The divmod() function takes two parameters and returns a tuple of their quotient and remainder i.e. it returns floor division and modulus of two numbers
Example
>>> divmod(5,11) (0, 5) >>> divmod(2,11) (0, 2) >>> divmod(11,2) (5, 1) >>>
enumerate()
The enumerate() function takes two parameters (iterable, start) and returns iterator for index and value of iterable.
It returns an enumerate objects.
The enumerate object yields pairs containing a count (from start, which defaults to zero) and a value yielded by the iterable argument. enumerate is useful for obtaining an indexed list: (0, seq[0]), (1, seq[1]), (2, seq[2]), …
Example
>>> for i in enumerate([10,20,30,40]): print(i) (0, 10) (1, 20) (2, 30) (3, 40) >>> for i in enumerate(['i','t','v','o','y','a','g','e','r','s'],1): print(i) (1, 'i') (2, 't') (3, 'v') (4, 'o') (5, 'y') (6, 'a') (7, 'g') (8, 'e') (9, 'r') (10, 's') >>>
eval()
The eval() function takes string as a argument which is parsed as expression.
Example
>>> eval('5*5')
25
>>> k=10
>>> eval('k-2')
8
>>>
float()
The float() function is use to convert int, string and boolean value to float.
Example
>>> float(3)
3.0
>>> float('30')
30.0
>>> float(True)
1.0
>>> float(False)
0.0
>>>
help()
The help() function provides a helpful message when ‘help’ is typed at the Python interactive prompt. Calling help() at the Python prompt starts an interactive help session. Calling help(thing) prints help for the python object ‘thing’..
Example
>>> help(bin)
Help on built-in function bin in module builtins:
bin(...)
bin(number) -> string
Return the binary representation of an integer.
>>> bin(2796202)
'0b1010101010101010101010'
>>> help(ord)
Help on built-in function ord in module builtins:
ord(...)
ord(c) -> integer
Return the integer ordinal of a one-character string.
>>>
hex()
The hex() function converts an integers to an hexadecimal numbers.
Example
>>> hex(10) '0xa' >>> hex(7) '0x7'
Note: The output of hex() has ‘0x’ in beginning which indicates that it is a hexadecimal number.
id()
The id() function returns identity of an object i.e. object’s memory address.
Example
>>> a=5 >>> id(a) 2009780752 >>> id([1,2,3])==id([3,2,1]) True
input()
The input() function reads a line from shell as a string data type and it can be converted to desirable data type using type conversion.
Example
>>> a=input("Enter name")
Enter name Itvoyagers
>>> b=int(input("Enter a value"))
Enter a value50
int()
The int() function converts a number or string to an integer, or return 0 if no arguments are given.
Example
>>> int(3.2)
3
>>> int('2')
2
len()
The len() function returns a length of an object. It calculates whitespace as a character. len() cannot calculate length of integers.
Example
>>> len('54687')
5
>>> len('hello python')
12
>>> len([5,6,4])
3
>>> len(121)
Traceback (most recent call last):
File "", line 1, in
len(121)
TypeError: object of type 'int' has no len()
list()
The list() function use to convert any compatible data type to list.
Example
>>> list({5,'k',6,'p'})
['k', 'p', 6, 5]
>>> list((5,'k',6,'p'))
[5, 'k', 6, 'p']
>>> list({1:'p',2:'h'})
[1, 2]
>>>
min() and max()
The min() function returns the smallest item from the iterable.
The max() function returns the largest item from the iterable.
Example
>>> max([4,5,6]) 6 >>> min([4,5,6]) 4 >>> max(['A','B','a']) 'a' >>> min(['A','B','a']) 'A' >>>
oct()
The oct() function converts an integers to an octal numbers.
Example
>>> oct(10) '0o12' >>> oct(7) '0o7' >>>
Note: The output of oct() has ‘0o’ in beginning which indicates that it is a octal number.
pow()
The pow() function takes two argument x,y and returns x**y.
Example
>>> pow(24,0.5) 4.898979485566356 >>> pow(2,2) 4 >>>
print()
It is the output function in python.
Example
>>> print("ITVoyagers")
ITVoyagers
str()
The str() function create a new string object from the given object.
Example
>>> str({5,'k',6,'p'})
"{'k', 'p', 6, 5}"
>>> str((5,'k',6,'p'))
"(5, 'k', 6, 'p')"
>>> str(552)
'552'
>>> str(9.5)
'9.5'
tuple()
If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable’s items. If the argument is a tuple, the return value is the same object.
Example
>>> tuple([1,5,6])
(1, 5, 6)
>>> tuple('hello')
('h', 'e', 'l', 'l', 'o')
>>> tuple({1:2,3:4})
(1, 3)
>>>
type()
The type() function returns datatype of a variable or a value. In python 2.x version type() returns
Example
>>> type(3.14)
<class 'float'>
>>> type(5)
<class 'int'="">
>>> type({5,8,9})
<class 'set'>
>>> type(30+2j)
<class 'complex'>
>>>
sum()
sum(iterable, /, start=0) the sum of a ‘start’ value (default: 0) plus an iterable of numbers When the iterable is empty, return the start value. This function is intended specifically for use with numeric values and may reject non-numeric types.
Example
>>> sum([2,4,6,8])
20
>>> sum({1,2,3})
6
round()
round(number, ndigits=None) Round a number to a given precision in decimal digits. The return value is an integer if ndigits is omitted or None. Otherwise the return value has the same type as the number. ndigits may be negative.
Example
>>> round(5.6) 6 >>> round(5.4) 5 >>> round(5.5) 6
range()
The range() function Return an object that produces a sequence of integers from start (inclusive) to stop (exclusive) by step. range(i, j) produces i, i+1, i+2, …, j-1. start defaults to 0, and stop is omitted! range(4) produces 0, 1, 2, 3. These are exactly the valid indices for a list of 4 elements. When step is given, it specifies the increment (or decrement).
Example
>>> range(1,5) range(1, 5) >>> range(5) range(0, 5) >>> list(range(5)) [0, 1, 2, 3, 4] >>> list(range(1,5)) [1, 2, 3, 4] >>>
For other built-in functions like set (), reversed(), sorted(), complex() etc we can make use of help() on python shell to get detailed description of functions.
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