python assign multiple outputs

Note that it is actually the comma which makes a tuple, not the parentheses. The parentheses are optional, except in the empty tuple case, or when they are needed to avoid syntactic ambiguity. Built-in Types - Tuples — Python 3.7.4 documentation

A tuple with one element requires a comma in Python

Each element has a type defined in the function.

Of course, specifying an index that exceeds the number of defined return values raises an error.

You can unpack and assign multiple return values to different variables.

Unpack a tuple and list in Python

Same for three or more return values.

Using [] returns list instead of tuple .

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Return multiple values from a function in Python

In this guide, we look at Python: Return multiple values from a function. We explain the various methods in detail and list their shortcomings.

Table of Contents - Python return multiple values:

Limitations and Caveats - Python return multiple values

Python return multiple values:.

Functions are used to perform a specific task which most likely involves returning a particular value. However, a few use-cases may require you to return two or more values. In other programming languages, the code to achieve this might be quite complex but Python provides a few handy methods to return multiple values.

Most of these methods involve using a collection data type to return these values. We have taken a close look at all of them below.

Using Comma-separated values (Tuples):

In this method, we use Python to return multiple values by simply separating them by commas. Python basically uses a tuple to achieve this.

A common confusion here is that the syntax of tuple requires a pair of brackets (). Although this is true, Python does not always require brackets to identify a tuple.

Using Python Lists:

Since they are a collection of items we could add values to the list and return the list.

In this method, you would have to use the index of the list to use the values individually.

Using a Python Dictionary:

In the previous method, accessing a particular value would be a hassle. However, this would not be a problem while using dictionaries to return multiple values. This is because we could use relevant key names and they could be accessed easily.

In this method, the returned values can easily be accessed within their keys.

Using a Python Data Class:

In this method, we use Data Classes to return multiple values. Data classes are a method of adding specific methods to a user-defined class. This method was introduced in Python version 3.7.

Multiple return

Python functions can return multiple variables. These variables can be stored in variables directly. A function is not required to return a variable, it can return zero, one, two or more variables.

This is a unique property of Python, other programming languages such as C++ or Java do not support this by default.

Introduction

Variables defined in a function are only known in the function. That’s because of the scope of the variable. In general that’s not a problem, unless you want to use the function output in your program.

In that case you can return variables from a function. In the most simple case you can return a single variable:

Call the function with complexfunction(2,3) and its output can be used or saved.

But what if you have multiple variables in a function that you want access to?

Create a function getPerson(). As you already know a function can return a single variable, but it can also return multiple variables.

This will output:

If you are a beginner, then I highly recommend this book.

Try the exercises below:

After completing these continue with the next exercise.

Download examples

How to Slice Lists/Arrays in Python

Python Scope of Variables

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Alternatives for returning multiple values from a Python function [closed]

The canonical way to return multiple values in languages that support it is often tupling .

Option: Using a tuple

Consider this trivial example:

However, this quickly gets problematic as the number of values returned increases. What if you want to return four or five values? Sure, you could keep tupling them, but it gets easy to forget which value is where. It's also rather ugly to unpack them wherever you want to receive them.

Option: Using a dictionary

The next logical step seems to be to introduce some sort of 'record notation'. In Python, the obvious way to do this is by means of a dict .

Consider the following:

(Just to be clear, y0, y1, and y2 are just meant as abstract identifiers. As pointed out, in practice you'd use meaningful identifiers.)

Now, we have a mechanism whereby we can project out a particular member of the returned object. For example,

Option: Using a class

However, there is another option. We could instead return a specialized structure. I've framed this in the context of Python, but I'm sure it applies to other languages as well. Indeed, if you were working in C this might very well be your only option. Here goes:

In Python the previous two are perhaps very similar in terms of plumbing - after all { y0, y1, y2 } just end up being entries in the internal __dict__ of the ReturnValue .

There is one additional feature provided by Python though for tiny objects, the __slots__ attribute. The class could be expressed as:

From the Python Reference Manual :

The __slots__ declaration takes a sequence of instance variables and reserves just enough space in each instance to hold a value for each variable. Space is saved because __dict__ is not created for each instance.