Python has a number of remarkable features when compared to other languages. It combines an easy-to-use syntax with an immense selection of specialized libraries. However, there’s one area where experienced programmers often find themselves struggling after picking up Python for the first time. And this is the language’s unique handling of indentation. This leads up to one of the more common errors people experience early on in their work with the language. The “taberror: inconsistent use of tabs and spaces in indentation” can be somewhat confusing at first since it deals with issues tightly bound to Python’s language structure. But the error is also relatively easy to fix.
What Does the Error Mean?
The tab error is essentially just alerting you to the fact that your code has an improper mix of tabs and whitespace. The language interprets indention from a tab and from your space key differently. If you’re using both in your code it can cause a tab error.
Looking Deeper Into the Tab Error
Python’s internal logic actually relies on what would simply be a stylistic option in most other languages. This is most notable in how it uses spaces. For example, many languages use braces to encapsulate a function. But this isn’t the case within Python code. Instead, programmers simply use whitespace or a tab after the function is defined.
Python’s use of whitespace means that it’s inherently more readable than code in many other languages. However, there is a downside to this decision. The language allows for use of both whitespace or tabs. But using both at the same time can cause problems. This usually results in a tab error of one kind or another.
Fixing the problem is usually fairly easy. You simply need to replace whitespace indentation with tabs or tabs with whitespace. Most IDEs even give you tools to automate the process. But if you’re looking at a smaller codebase or a single instance of this error then you can also simply fix it by hand. Let’s look at an example of this Python error and how we could fix it.
Fixing the Tab Error
The error itself can be a little difficult to reproduce thanks to the fact that various programs often ignore the differences between tabs and whitespace. The process of moving text from browser to IDE or text file can often remove the formatting errors or introduce new ones. As such, you’ll need to begin by typing out this example. It’s best to do so in a plain text file with a simple program like notepad. More advanced editors or IDEs might try to automatically fix these issues for you. And we need to make sure we can create the error before moving on to fix it by hand. Type out the following code without using any tabs or spaces.
def example(first,second,third):
x = first+second
final = x*third
return final
ourNum = example(5,1,8)
print(ourNum)
If you run this Python code as-is you’ll receive an entirely different type of error. The resulting indention error highlights how Python’s interpreter uses whitespace rather than enclosing characters to work with functions. In short, the interpreter’s indention error complains that you haven’t indented the declaration of x to signal that it’s part of the example function.
In your text editor, place your cursor before the x declaration and press the tab key. Then place your cursor before the declaration of final and press your keyboard’s space key until the f in final lines up with the x declaration. Then use either method to indent the next line where the final value is returned. Finally, save the file as a python script. The result should look like the following code.
def example(first,second,third):
x = first+second
final = x*third
return final
ourNum = example(5,1,8)
print(ourNum)
The declaration of x and final both appear to use the same format. However, when you run this code it should give the “inconsistent use of tabs and spaces in indentation” error message.
Fixing the problem is simple. You just need to delete the white space and use tab instead. The easiest method to do so, in this case, would be to simply place your cursor and hit backspace until the formatting is removed from both lines. You can then indent them again with the tab key. After saving and running the python script you should see the number 48 printed to the screen and no error messages. Of course, this method of fixing the error wouldn’t be very efficient if you were looking at code with hundreds or even thousands of tab errors. Thankfully most Python-focused IDEs provide tools to automatically deal with the issue.
Every IDE will have different options to unify whitespace indentation. You may even have to use a text replace option. But the taberror is a common enough issue that Python IDEs will usually detect it on their own and offer an automated solution. For example, if you copy and paste the error-producing code from a plain text file to the PyCharm IDE then you’ll notice a lightbulb hint notification. It will then ask you if you want to convert indents to space, space to indent, or possibly even reformat the code. Each of these options will take a different path to the same ultimate end point where your code uses consistent whitespace.