Python Built-in Functions

Introduction to Python Built-in Functions

Built-in functions are the functions that are pre-defined in the programming language’s library, for the programming to directly call the functions wherever required in the program for achieving certain functional operations. A few of the frequently used built-in function in the Python programs are abs(x) for fetching the absolute value of x, bin() for getting the binary value, bool() for retrieving the boolean value of an object, list() for lists, len() to get the length of the value, open() to open the files, pow() for returning the power of a number, sum() for fetching the sum of the elements, reversed() for reversing the order, etc.

Examples of Python built-in functions

Here are the examples of python built-in functions mention below

1. abs(x)

Returns the absolute value of a number. In case a complex number is passed, the magnitude of that number is returned. It is the same as the distance from the origin of a point on an x-y graph. For eg-

Abs(-3) =3

abs(3+4i) = 5

Code:

a = 12
b = -4
c = 3+4j
d = 7.90
print(abs(a))
print(abs(b))
print(abs(c))
print(abs(d))

Output:

2. all(x)

Same as logical ‘and’ operator. That means it will return true if all variables in the iterator are true. Here iterable objects are referred to tuple, lists, dictionary.

A variable is said to be true in python if it is non-zero and not NONE. Here NONE is a keyword defined in python that is considered null.

For eg= if iterable ‘item’ contains value ‘2,4,5,6,1’ – Result will be true .

If item1= ‘2,0,4,5’ – Result will be false

Code:

tuple = (0, True, False)
x = all(tuple)
print(x)

output:

Explanation – Here all() returns False because the first and third value in the tuple is false.

Code:

sampledict = {0 : "Apple", 1 : "Orange"}
x = all(sampledict)
print(x)

output:

Explanation- Here all() returns False because one of the keys is false and in case of dictionaries only the keys are checked not the values.

3. any(x)

This function is the same as the logical ‘OR’ operator that returns False only if all the variables present in an iterable are false. Here iterable refers to the tuple, dictionary, and lists.

Note- For an empty iterable object any() returns False.

For example- any(2,3,4,5,9) – True

Any(2,0,9,1,8) – Returns False

Code:

myset = {0, 1, 0}
x = any(myset)
print(x)

Output:

Explanation-  In the above program, any function returns True a the set is given is having at least one True value.

4. bin()

This function returns the binary value of a number.

Code:

a=5
print(bin(a))

Output:

5. round()

It gives roundoff value for a number i.e gives the nearest integer value for a number. This function accepts one argument either decimal, float or integer and gives roundoff output.

Code:

print(round(4.5))
print(round(-7.7))

Output:

6. bin()

It returns binary value for the number passed in the argument. The only integer can be passed as an argument to the function.

Code:

print(bin(4))
print(bin(9))

Output:

7. bool()

This function returns the Boolean value of an object.

Code:

print(bool(0))
print(bool(-4.5))
print(bool(None))
print(bool("False"))

Output:

8. bytearray()

This function returns a new array of bytes i.e mutable sequence of integers from range 0 to 256.

Syntax – bytearray(source,encoding,errors)

Note-

1. The values to function are optional.
2. If any non-ascii value is given to the function, it gives the error -TypeError: string argument without an encoding

Code:

print(bytearray())
print(bytearray('Python','utf-8'))

Output:

9. compile()

It is used to generate Python code object from string or an AST object.

Following is the syntax for the function –

Compile(source,filename,mode,flags=0,dont_inherit=False,optimize=-1)

The output of this function is given as an argument to eval() and exec() function.

Code:

myCode = 'a = 7\nb=9\nresult=a*b\nprint("result =",result)'
codeObject = compile(myCode, 'resultstring', 'exec')
exec(codeObject)

Output:

10. list()

This function is used to convert an object to the list object.

Syntax – list([iterable])

Here iterable refers to any sequence such as string, tuples, and iterable object or collection object such as a set or dictionary.

A mutable sequence of the list of elements is returned as an output of this function.

Code:

print(list()) #returns empty list
stringobj = 'PALINDROME'
print(list(stringobj))
tupleobj = ('a', 'e', 'i', 'o', 'u')
print(list(tupleobj))
listobj = ['1', '2', '3', 'o', '10u'] print(list(listobj))

Output:

11. len()

This function givens the length of the object as an output.

Syntax – len([object])

Here objects must be either a sequence or collection.

Note- Interpreter throws an error in case it encounters no argument given to the function.

Code:

stringobj = 'PALINDROME'
print(len(stringobj))
tupleobj = ('a', 'e', 'i', 'o', 'u')
print(len(tupleobj))
listobj = ['1', '2', '3', 'o', '10u'] print(len(listobj))

Output:

12. max()

This function returns the largest number in the given iterable object or the maximum of two or more numbers given as arguments.

Syntax – max(iterable) or max(num1,num2…)

Here iterable can be list, tuple, dictionary or any sequence or collection.

Code:

num = [11, 13, 12, 15, 14] print('Maximum is:', max(num))

Output:

Note- In case no arguments are given to the function then ValueError is thrown by the interpreter.

13. min()

This function returns minimum value from the collection object or the values defined as arguments.

Syntax – min([iterable])

Code:

print(min(2,5,3,1,0,99))
sampleObj = ['B','a','t','A'] print(min(sampleObj))

Output:

Note– In case no arguments are given to the function then ValueError is thrown by the interpreter.

14. map()

This function helps in debugging as it provides the result after an operation is applied to each of the items in an iterable object.

Syntax – map(fun,[Iterable])

where iterable can be a list, tuple, etc..

Code:

numList = (11, 21, 13, 41)
res = map(lambda x: x + x, numList)
print(list(res))

Output:

15. open()

This function returns a file object after opening a particular file that helps to read or write into that file.

Syntax – open(file, mode)

file -refers to the name with the complete path of the file to read or written into.\

mode- refers to the manner or the work we need to perform with the file. It can value like ‘r’,’a’,’x’ etc.

Code:

f = open("myFile.txt", "r")#read mode
print(f.read())

Output:

16. pow()

This function returns the value of the power of 1 number to another number.

Syntax – pow(num1,num2) where num1,num2 must be an integer, float or double.

Code:

print(pow(2,-3))
print(pow(2,4.5))
print(pow(3,0))

Output:

17. oct()

This function helps to generate the octal representation of a number.

Syntax – oct(number) where the number can be an integer, hexadecimal or binary number.

Code:

print("The octal representation of 32 is " + oct(32))
print("The octal representation of the ascii value of 'A' is " + oct(ord('A')))
print("The octal representation of the binary of 32 is " + oct(100000))
print("The octal representation of the binaryof 23 is " + oct(0x17))

Output:

18. sorted()

This function has made the sorting of the numbers very easy.

Syntax – sorted(iterable,key,reverse)

Here, iterable – refers to the list, tuple or any collection of objects that needs to be sorted.

Key – refers to the key on which the values must be sorted.

Reverse- this can be set to true to generate the list in descending order.

The output of this function is always a list.

Code:

sampleObj = (3,6,8,2,5,8,10)
print(sorted(sampleObj,reverse=True))
sampledict = {'a':'sss','g':'wq','t':2}
print(sorted(sampledict,key= len))

Output:

19. sum()

This function helps to sum the member of an iterable object.

Syntax – sum([iterable],start)

Iterable refers to any iterable object list, tuple or dictionary or sequence of numbers.

Start – this marks the initialization of the sum result that needs to be added to the final result. It is an optional argument.

Code:

num = [2.5, 3, 4, -5] numSum = sum(num)
print(numSum)
numSum = sum(num, 20)
print(numSum)

Output:

20. str()

This function helps to generate the printable representation of an Object.

Syntax – str(object,encoding,errors) where encoding and errors are optional.

Code:

print(str('A1323'))
b = bytes('pythön', encoding='utf-8')
print(str(b, encoding='ascii', errors='ignore'))
#errors='ignore' helps interpreter to ignore when it found a non Ascii character

Output:

21. type()

This function is used to print the type or the class the object passed as an argument belongs to. This function is used for debugging purposes.

Syntax – type(Object)

It is also sometimes used to create a new object

Syntax- type(name,bases,dict)

Code :

tupleObj=(3,4,6,7,9)
print(type(tupleObj))
new1 = type('New', (object, ),
dict(var1 ='LetsLearn', b = 2029))
print(type(new1))

Output :

22. callable()

This function returns True if the object passed as argument is callable.

Syntax – callable(Object)

Code:

def myFun():
return 5
res = myFun
print(callable(res)) #function is called to get this value
num1 = 15 * 5
print(callable(num1))#no function is called

Output:

23. input()

This function helps python to take input from the user. In python 2.7 Its name as raw_input() which has been changed to input(). Once enter or esc is pressed system is resumed again.

Syntax – input()

24. range()

This function returns the series of numbers between 2 specific numbers. This is very useful while dealing with a loop in a program as it helps to run a loop in a specific number of times.In python 3.6 – xrange() has been renamed as range().

Syntax – range(start,stop,step)

Here, start- an Integer which marks the start of the series.

A stop-an integer which marks the last number of the series. The last number in the range is stop-1.

Step – an integer that lets to increment the loop with a specific number. By default, it is +1.

Code: 

res = 1
for i in range(1, 10,2):
res = res * i
print("multiplication of first 10 natural number :", res)

Output:

Note- Float numbers as an argument throws an error.

25. reversed()

This function returns an iterator to access the collection in reverse order.

Syntax– reversed([sequence] or [collection])

Code:

tupleObj=(3,4,6,7,9)
for i in reversed(tupleObj):
print(i,end=' ')

Output:

Conclusion

Python has a vast library that contains a lot of the number of functions and these are defined only to ease down the work of a developer. These functions are known as built-in functions. They must be used in the way they are defined and are not advised to be overridden as it can cause side effects to the working and can lead to wrong output.

Recommended Articles

This is a guide to Python Built-in Functions. Here we discuss the Examples of Python Built-in Functions with the codes and outputs. You may also look at the following article.

1. Python Data Types
2. Python Features
3. Python Sets
4. Fibonacci Series in Python