Python getattr() Function
The python getattr() function returns the value of a named attribute of an object. If it is not found, it returns the default value.
Python getattr() Function 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
Python globals() Function
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.
Python globals() Function Example
age = 22
globals()['age'] = 22
print('The age is:', age)
Output:
The age is: 22
Python hasattr() Function
The python any() function returns true if any item in an iterable is true, otherwise it returns False.
Python hasattr() Function 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
Python iter() Function
The python iter() function is used to return an iterator object. It creates an object which can be iterated one element at a time.
Python iter() Function 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
Python len() Function
The python len() function is used to return the length (the number of items) of an object.
Python len() Function Example
strA = 'Python'
print(len(strA))
Output:
6
Python list()
The python list() creates a list in python.
Python list() 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]
Python locals() Function
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.
Python locals() Function Example
def localsAbsent():
return locals()
def localsPresent():
present = True
return locals()
print('localsNotPresent:', localsAbsent())
print('localsPresent:', localsPresent())
Output:
localsAbsent: {}
localsPresent: {'present': True}
Python map() Function
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.).
Python map() Function 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}
Python memoryview() Function
The python memoryview() function returns a memoryview object of the given argument.
Python memoryview () Function 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]
Python 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.
Python object() 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__']
Python open() Function
The python open() function opens the file and returns a corresponding file object.
Python open() Function 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.
Python chr() Function
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.
Python chr() Function 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)
Python 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.
Python complex() 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)
Python delattr() Function
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.
Python delattr() Function 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
Python dir() Function
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.
Python dir() Function Example
# Calling function
att = dir()
# Displaying result
print(att)
Output:
['__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__',
'__name__', '__package__', '__spec__']
Python divmod() Function
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
Python divmod() Function Example
# Python divmod() function example
# Calling function
result = divmod(10,2)
# Displaying result
print(result)
Output:
(5, 0)
Python enumerate() Function
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.
Python enumerate() Function 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)]
Python 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.
Python dict() 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}
Python filter() Function
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.
Python filter() Function 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]
Python hash() Function
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.
