The keyword “yield” is a important part of the Python programming language, and it can be used in a number of different ways. In this article, we’ll take a closer look at what the yield keyword does in Python, and how it can be used to create more efficient and powerful programs.
The primary use of the yield keyword is to create a generator function. A generator function is a special type of function that produces a sequence of values, one at a time, when it is called. Unlike a regular function, which executes all of its code and returns a single value, a generator function can be paused at any point and resumed later, allowing it to produce a potentially infinite sequence of values.
To create a generator function in Python, you simply use the yield keyword in place of the return keyword. For example, here is a simple generator function that produces a sequence of numbers:
def count_up_to(max): count = 1 while count <= max: yield count count += 1
When this generator function is called, it will execute the code until it encounters the yield keyword, at which point it will pause and return the value of “count” to the caller. The generator function can then be resumed from where it left off the next time it is called, allowing it to produce the next value in the sequence.
Generator functions are particularly useful when you need to work with large sequences of data, as they allow you to process the data one piece at a time, rather than having to load it all into memory at once. They are also useful for creating infinite sequences, such as an infinite stream of random numbers.
In addition to creating generator functions, the yield keyword can also be used in the body of a regular function to produce a generator object. When a function contains a yield statement, it becomes a generator function, even if it does not use the “yield” keyword in its definition.
Here is an example of a regular function that uses the yield keyword to produce a generator object:
def even_numbers(max): for num in range(max): if num % 2 == 0: yield num
This function will produce a generator object that produces all of the even numbers up to the specified maximum value.
In summary, the yield keyword is a powerful tool in Python that allows you to create generator functions and generator objects. Generator functions and objects are useful for working with large sequences of data and for creating infinite sequences, and they can help you create more efficient and powerful programs in Python.