How to Yield Values from List in Python

The yield keyword in Python produces a series of values one at a time and is used with the generator function, it works the same as the return keyword the difference being that the yield keyword produces a sequence of values one at a time. In this article, we will explore different approaches to yield values from a list in Python.

Yield Values from List in Python

Below are the possible approaches to Yield Values From a List In Python:

• Using Basic Generator
• Using itertools.repeat() Function
• Using a map with a generator function:

Yield Values From List Using Basic Generator

In the below approach code, the generatorFn() function is a basic generator that yields values from the data list. The yield statement is used to produce each value one at a time. The for loop is then used to iterate over the generated values and print them.

Python3

def generatorFn():
    data = ["Python", "Java", "C++", "JavaScript", "HTML", "CSS"]

    for language in data:
        yield language

# Using the generator to iterate over the values
for value in generatorFn():
    print(value)

Output

Python
Java
C++
JavaScript
HTML
CSS

Yield Values From List Using itertools.repeat()

In the below approach code, it uses itertools.repeat to repeat the given list (data) a specified number of times (repeat_count), and yield from is used to yield each element, resulting in a single iteration through the repeated list. The repeat_count of 1 ensures a single iteration without an infinite loop.

Python3

from itertools import repeat

def yield_using_repeat(lst, repeat_count):
    for item in repeat(lst, repeat_count):
        yield from item

data = ["Python", "Java", "C++", "JavaScript", "HTML", "CSS"]
repeat_count = 1

for language in yield_using_repeat(data, repeat_count):
    print(language)

Output

Python
Java
C++
JavaScript
HTML
CSS

Yield Values From List Using a map With a Generator Function

In the below approach, yield_values_generator is a generator function that yields values from the input list. The map function is then used to apply the lambda function to each generator element, effectively yielding the values from the list. Finally, the for loop iterates through the result of the map and prints each language

Python3

def yield_values_generator(lst):
    for item in lst:
        yield item

data = ["Python", "Java", "C++", "JavaScript", "HTML", "CSS"]

generator_result = map(lambda x: x, yield_values_generator(data))

for language in generator_result:
    print(language)

Output

Python
Java
C++
JavaScript
HTML
CSS