Methods and Functions

Python next()

The python next function is responsible for returning the next item in the iterator. The function takes two arguments as the input, i.e, the iterator and a default value. Then the function returns the element. The python next method calls on iterators and throws an error if no item is present. We can set a default value to avoid the error.

python next

Source Code

Syntax

next(iterable, default)

next() Parameters

The parameters of the next function are mentioned below:

  1. Iterable- This is a required argument. This parameter retrieves the iterator’s next item.
  2. Default- default is an optional parameter. The default value is returned if there is no next item and the iterator is exhausted.  

Return Value from next()

The python next function is used to return the next item from the iterator. 

If there are no items present, the iterator gets exhausted, and it returns the default value to avoid any errors. If the default parameter is not given, and the iterator is exhausted then the StopIteration exception will arise. 

What does next in python do?

The next() function returns the iterator’s next item. Look at the examples given below:

Example 1: Get the next item

In the program given below, you can observe that the last statement causes an error. The error was caused because there was no next item available, and the iterator got exhausted. 

Source Code

                    

random = [52, 19, 'catto']


# converting the list to an iterator

randomm_iterator = iter(random)

print(randomm_iterator)

# Output: 52

print(next(randomm_iterator))

# Output: 19

print(next(randomm_iterator))

# Output: 'catto'

print(next(randomm_iterator))


# The last statement will cause an 

# error because the iterator has 

#been exhausted

print(next(random_iterator))

Output

52

19

catto

Traceback (most recent call last):

  File "python", line 18, in 

StopIteration

Example 2: Passing default value to next()

No error is raised, as a default value has been provided.

Source Code

                    

random = [45, 93]


# transforming a list into an iterator

randomm_iterator = iter(random)


# Output: 45

print(next(randomm_iterator, '-1'))



# Output: 95

print(next(randomm_iterator, '-1'))

# random_iterator is exhausted

# Output: '-1'

print(next(randomm_iterator, '-1'))

print(next(randomm_iterator, '-1'))

print(next(randomm_iterator, '-1'))

Output

5

9

-1

-1

Does Python have next?

Yes, the next() function returns the next item from the iterator, this can be done without the help of any indices or loops. Let’s look at some examples of the next() to see how it works.

Example 1: Getting the next items from the iteration without using any loops. 

Source Code:

                    

numb = iter([256, 312, 812]) # Creating iterator  

# Calling function  

itemm = next(numb)   

# Displaying the result  

print(itemm)  

# displaying the second item  

itemm = next(numb)  

print(item)  

# displaying the third item  

itemm = next(numb)  

print(itemm)  

Output:

256

32

82

Example 2: When the method reaches the end of the program with no default value, the function returns an error.

Source Code:

                    

numb = iter([256, 32, 82]) # Initializing the iterator  

# Calling function  

i = next(numb)   

# Displaying the result  

print(i)  

# displaying the second item  

i = next(numb)  

print(i)  

# displaying the third item  

i = next(numb)  

print(i)  

# displaying the fourth item  

i = next(numb) # error raised as no item is present  

print(i)  

Output:

Traceback (most recent call last): 

  File "source_file.py", line 14, in 

    item = next(number)

StopIteration 

256

32

82

 

Example 3: Setting a default value in case of an error

Source Code

                    

numb= iter([26, "python", 812,]) 


# Creating the iterator  

# Calling function  

i = next(number)   

# Displaying result  

print(i)  

# displaying the second item  

i = next(number)  

print(i)  

# displaying the third item  

i = next(number)  

print(i)  

# displaying the fourth item  

i = next(number, "No item is present") # default value is given 

print(i)  

Output:

26

python

812

No item is present

What is __ next __ in Python?

The _next_ is an iterator in the Python programming language that is used to return the data when the object is called upon, one element at a time.  The next item in the series must be returned using the __next__() method. It must raise StopIteration when it reaches the end. 

Example:

                    

mylist = [14, 7, 10, 3]


# get an iterator using iter()

myiter = iter(mylist)


# iterate through it using next()


# Output: 14

print(next(myiter))



# Output: 7

print(next(myiter))



# next(obj) is same as obj.__next__()



# Output: 10

print(myiter.__next__())



# Output: 3

print(myiter.__next__())



# This will result in an error

next(myiter)

Output

14

7

10

3

Traceback (most recent call last):

  File "", line 24, in 

    next(my_iter)

StopIteration

How do you go to the next iteration in Python?

The next() in python allows the users to access the next method in the iteration. Here’s an example of how the next() functions:

Source Code:

                    

list11 = [1, 2, 3, 4, 5]
  

# converting list to iterator

list11 = iter(list11)

  

print ("The elements of the list are: ")

  

# printing using next()

# using default

while (1) :

    value = next(list11,'end')

    if value == 'end':

        print ('list end')

        break

    else :

        print (value)



Output:

The elements of the list are: 

1

2

3

4

5

list end44

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