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Convert Generator Object To List in Python

Last Updated : 06 Feb, 2024
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Python, known for its simplicity and versatility, provides developers with a plethora of tools to enhance their coding experience. One such feature is the generator object, which allows for efficient iteration over large datasets without loading them entirely into memory. In this article, we’ll explore the methods behind converting generator objects to lists and how to perform this transformation in Python.

Convert Generator Object To List

Below, are the ways to Convert Generator Object To List in Python.

Convert Generator Object To List Using Built-in Function

In this example, the below code defines a Fibonacci number generator using a Python generator function. It creates a generator object `fib_gen` that yields the first 10 Fibonacci numbers. The generator object is then converted to a list `fib_list`.

Python3




# Fibonacci generator
def fib(num):
    a, b = 0, 1
    for _ in range(num):
        yield a
        a, b = b, a + b
  
# Create a generator object
fib_gen = fib(10)
print(type(fib_gen))
  
# Convert to list
fib_list = list(fib_gen)
print(fib_list)
print(type(fib_list))


Output

<class 'generator'>
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
<class 'list'>

Convert Generator Object To List Using List Comprehension

In this example, below code creates a generator object `gen` using a generator expression that produces numbers from 0 to 9. It then converts the generator object to a list `lst` using a list comprehension .

Python3




# create a generator object
gen = (x for x in range(10))
print(type(gen))
  
# convert to list through comprehension
lst = [i for i in gen]
print(lst)
print(type(lst))


Output

<class 'generator'>
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
<class 'list'>

Convert Generator Object To List Using extend() Method

In this example, below code creates a generator object `gen` using a generator expression that produces numbers from 0 to 9. It then creates an empty list `lst` and extends it with the values generated by the generator.

Python3




# create a generator object
gen = (x for x in range(10))
print(type(gen))
  
# create an empty list and extend
lst = []
lst.extend(gen)
print(lst)
print(type(lst))


Output

<class 'generator'>
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
<class 'list'>

Convert Generator Object To List Using ‘*’ operator

In this example, ebcode creates a generator object `gen` using a generator expression that produces numbers from 0 to 9. It then unpacks the generator into a list `lst` using the `*` (unpacking) operator, resulting in a list containing the generated values.

Python3




# create a generator object
gen = (x for x in range(10))
print(type(gen))
  
# unpack generator into a list
lst = [*gen]
print(lst)
print(type(lst))


Output

<class 'generator'>
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
<class 'list'>

Conclusion

In Conclusion, converting a generator object to a list in Python provides a balance between memory efficiency and the need for immediate access to data. This transformation is beneficial for scenarios requiring eager evaluation, caching, or multiple iterations, allowing developers to optimize the performance of their code based on specific requirements.



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