3.1.4.11 Lists - collections of data | lists and loops

Lists in action

Let's leave lists aside for a short moment and look at one intriguing issue.

Imagine that you need to rearrange the elements of a list, i.e., reverse the order of the elements: the first and the fifth as well as the second and fourth elements will be swapped. The third one will remain untouched.

Question: how can you swap the values of two variables?

Take a look at the snippet:

variable1 = 1 variable2 = 2 variable2 = variable1 variable1 = variable2

If you do something like this, you would lose the value previously stored in variable2. Changing the order of the assignments will not help. You need a third variable that serves as an auxiliary storage.

This is how you can do it:

variable1 = 1 variable2 = 2 auxiliary = variable1 variable1 = variable2 variable2 = auxiliary

Python offers a more convenient way of doing the swap - take a look:

variable1 = 1 variable2 = 2 variable1, variable2 = variable2, variable1

Clear, effective and elegant - isn't it?

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