In this Blog, i will be covering few of Python Built-In Functions that will be useful for developers.
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. These functions are known as Built-in Functions. There are several built-in functions in Python , Lets discuss few of them which is useful for developers in day to day development.
Python all() Function
The python all() function accepts an iterable object (such as list,dictionary etc.).
1. It returns True if all items in passed iterable are true, otherwise it returns False.
2. If the iterable object is empty, the all() function returns True.
Let's take an example of all() functions and see how it works
Example1
# all values true
number = [1, 3, 4, 5]
print(all(number)) - returns True
Example 2
# all values false
number = [0, False]
print(all(number)) - returns False
Example 3
# one false value
number = [1, 3, 4, 0]
print(all(number)) - returns False
Example 4
# one true value
number = [0, False, 5]
print(all(number)) - returns False
Example 5
# empty iterable
number = []
print(all(number)) - returns True
Python bool() Function
The python bool() method converts value to boolean (True or False) using the standard truth testing procedure.
1. It is not mandatory to pass value to bool().
2. If you do not pass the value, bool() returns False.
3. In general, bool() takes a single parameter value.
Let's take few example and try to understand how it works
Example 1
test = []
print(bool(test)) - returns False
Example 2
test = [0]
print(bool(test)) - returns True
Example 3
test = 0.0
print(bool(test)) - returns False
Example 4
test = None
print(bool(test)) – returns False
Example 5
test = True
print(bool(test)) - returns True
Example 6
test = 'Easy string'
print(test,'is',bool(test)) - returns True
Python callable() Function
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.
Parameters
object - The object that you want to test and check, it is callable or not.
Return
Returns True if the object is callable, otherwise False.
Lets take an example and try to understand its working
Example 1
Check if a function is callable:
def x():
a = 5
print(callable(x)) - returns True
Example 2
Check if a function is not callable (such as normal variable).
x = 5
print(callable(x)) - returns False
Python exec() Function
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.
Signature
exec(object, globals, locals)
Parameters
object - It should be either string or code object.
globals (optional) - It is used to specify global functions.C++ vs Java
locals (optional) - It is used to specify local functions.
Lets take few examples of working of exec function
Example 1
x = 5
exec('print(x==5)') - returns True
exec('print(x+4)') - returns 9
Example 2 - This example shows exec() dynamic code execution
from math import *
for l in range(1, 3):
func = input("Enter Code Snippet to execute:\n")
try:
exec(func)
except Exception as ex:
print(ex)
break
print('Done')
Output
Enter Code Snippet to execute:
print(sqrt(16))
4.0
Enter Code Snippet to execute:
print(min(2,1))
1
Done
Python eval() Function
The python eval() function parses the expression passed to it and runs python expression(code) within the program.
Signature
eval(expression, globals, locals)
Parameters
expression - The string is parsed and evaluated as a Python expression. globals (optional) - A dictionary that specifies the available global methods and variables. locals (optional) - It is an another dictionary which is commonly used for mapping type in Python.
Return
It returns the result evaluated from the expression.
Lets take an example of eval function
x = 5
print(eval('x + 1')) - returns 6
Note :-
In this example, we take an integer variable named x, and eval() function parses the expression and returns result evaluated from the expression.
Python frozenset() Function
The python frozenset() function returns an immutable frozenset object initialized with elements from the given iterable.
Signature
frozenset(iterable)
Parameters
iterable: An iterable object such as list, tuple etc.
Return
It returns an immutable frozenset object initialized with elements from the given iterable.
Lets take an example and try to understand how it works
# 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()
Explanation:
In the above example, we take a variable that consists tuple of letters and returns an immutable frozenset object.
Python hasattr() Function
The python hasattr() function returns true if an object has given named attribute. Otherwise, it returns false.
Signature
hasattr(object, attribute)
Parameters
object: It is an object whose named attribute is to be checked. attribute: It is the name of the attribute that you want to search.
Return
It returns true if an object has given named attribute. Otherwise, it returns false.
Lets take an example and try to understand its working
class Employee:
age = 38
name = 'Dhiraj Kumar'
employee = Employee()
print('Employee has age?:', hasattr(employee, 'age'))
print('Employee has salary?:', hasattr(employee, 'salary'))
Output:
Employee has age?: True
Employee has salary?: False
Explanation:
In this example, we have created a class named as Employee, then we create the object of the Employee class, i.e., employee. The hasattr(employee, 'age') returns the true value as the employee object contains the age named attribute, while hasattr(employee, 'salary')) returns false value as the employee object does not contain the salary named attribute.
That's all for this Blog developers and with that, it's a wrap! I hope you found the article useful.
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