Difference Between Python Yield and Python Return

Yield and return are terms that are very commonly used while programming in python. Essentially, they are keywords that are used to pass values between functions.

However, for those who do not deal with programming concepts regularly, it may get quite difficult to understand how each of them is different.

Python Yield vs Python Return

The main difference between python yield and python return is that the yield keyword in python is used by programmers to only pause the execution of a function for a certain amount of time whereas the return keyword in python is used by programmers to completely stop the execution of a function.

Python Yield vs Python Return

Python yield is essentially a keyword that is extensively used in programming. It pauses the execution of a function for a programmer.

This allows returning without affecting the state of other variables. When the yield keyword is used in a function, its execution begins only after the statement is made, which is from where it was left off.

Meanwhile, python return has a very similar purpose. it ‘returns’ the resulting value to the programmer.  This is where it gets its name from.

However, the keyword is used to end the execution of the function completely. Further, when used in a function, all the statements made after it are not capable of execution.

Comparison Table Between Python Yield and Python Return

Parameters of ComparisonPython YieldPython Return
MeaningIt is a keyword that returns values to the programmer without affecting other variables.It is a keyword that returns values to the programmer while completely destroying other variables.
ExecutionIt pauses the execution of a function for a certain period.It ends the execution of the function.
UsageIt is only used in generator functions.It is only used in normal functions.
OperationThe values returned are in the form of a series.Only a single value is returned.
RunningIt can be used multiple times in a function.It can only be used once in a function.
Data sizeIt is used when the data size is large.It is used when the data size is not as large.
SpeedIt facilitates faster execution for large sets of data.It does not facilitate fast execution for large sets of data.

What is Python Yield?

Yield is a keyword that is extensively used in python. It pauses the execution of a program and returns a series of values to the caller at that point.

Further, when the statement is dismissed, the function begins execution right back from where it left. During this, no other local variables are affected in any way.

However, this keyword is only used in generator functions. These are specific functions that are not capable of returning single values. Therefore, they are entirely based upon python yield.  

Furthermore, the keyword can be included in such function more than one time. This is because the function does not get destroyed, and neither do the local variables.

The way yield keyword works in python is very different from other keywords performing a similar function. When there is an iteration, the code is run in python to find the yield statement.

On encountering it, the code stops. Further, the yielded value is sent back to the caller while the execution of the function remains paused.

Python yield is the best choice for usage in case the data sets are very large. The keyword is known to facilitate efficiency and fast execution in such a case.

What is Python Return?

Return is another keyword in Python that has a very similar function as yield. However, unlike the former, it does not ‘pause’ execution but completely stops it.

In doing so, it sends a single value back to the caller. Meanwhile, the entire function is completely destroyed along with local variables. This means that it can no longer be executed.

This keyword only works in normal function. However, it can only be used one time. This is because when it is used, the remainder of the function is destroyed.

This leaves no space for further coding. However, it must be noted that only the particular function using the return statement is affected. The rest of the code can still run without hassle.

Using the keyword in a function allows a caller to process data efficiently. This data can be sent to the main program. Further, it can be used in another function of the same code. 

However, a drawback of using the return statement is that it is not the optimal choice for large sets of data. It does not run at a fast speed and can often become time-consuming. This affects the overall productivity of the function as well as the caller.

Main Differences Between Python Yield and Python Return

  1. Python yield is a keyword that returns values to the programmer without affecting other variables whereas python return is a keyword that returns values to the programmer while completely destroying other variables.
  2. Python yield pauses the execution of a function for a certain period whereas python return ends the execution of the function.
  3. Python yield is only used in generator functions whereas python return is only used in normal functions.
  4. In the case of python yield, the values returned are in the form of a series whereas in the case of python return only a single value is returned.
  5. Python yield can be used multiple times in a function whereas python return can only be used once in a function.
  6. Python yield is used when the data size is large whereas python return is used when the data size is not as large.
  7. Python yield facilitates faster execution for large sets of data whereas python return does not facilitate fast execution for large sets of data.

Conclusion

Python yield and python return are two keywords with a very similar function. Each of them returns values to the caller while executing a function. However, yield returns a series of values whereas return brings back only one value.

Moreover, while doing so, yield only pauses the execution of the function. On the other hand, return stops the execution of a function completely.

Another major difference between the two is that yield can be used in a function more than one time. Meanwhile, the return keyword can only be used in a function once. This is because when used, return stops the function from execution.

References

  1. https://dl.acm.org/doi/abs/10.1145/2544173.2509536
  2. https://link.springer.com/chapter/10.1007/978-3-319-77935-5_14
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