Specifying order in categorical variables

It is common to have a categorical column whose values have a clear order. This can be shirt sizes, like “S”, “M”, “L” or “XL”. The category “L” is greater than “M”.

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Applying ordering to the values

To do this, we reach out to the column menu and select the Order option.

All the different values for this column will appear, with a handle on the left. Drag and sort the categories in the order you want, in descending order. Bigger elements first.

Hit save and you are good to go!

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Using the recipe

We can also order categories through the Recipe, writing a step.

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Intro and Resources

To do this, we are going to use the order_categories step. You can follow this example.

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Open the Recipe

Reach out to the little scroll icon in the top right corner.

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Enable Code Mode

This will allow us to see and edit the code.

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Search for the order_categories step

Look for a line of code that looks like this:

create_project(ds)

and write a new line ABOVE it. It is very important that you keep this in mind. Our step won’t have any effect if it is written after the create_project step.

Start writing ord, and the list will show the order_categories step.

Press enter, tab or click on the suggestion to accept it.

This operation will write this piece of code on the same line:

order_categories(ds.input) -> (ds.output)

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Edit the step with your column name

Because the column we want to take the information from is called size (careful, it’s case sensitive!), we change the code so it looks like this:

order_categories(ds.size) -> (ds.size)

This gives an error because we are trying to create a column that already exists, size. We can either create a new column with the ordering applied, or we can overwrite the existing column to include the ordering information.

To create a new column, simply change the output from size to any other name, for example:

order_categories(ds.size) -> (ds.size_ordered)

To overwrite the colum, we use the overwrite operator, like this:

order_categories(ds.size) => (ds.size)
                          ^ this changed from - to =

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Apply the ordering

Let’s apply the ordering. To do this, edit the step like this:

order_categories(ds.size,
    {"categories": ["XXS", "S", "M", "L", "XXL", "XXXL"]}
) => (ds.size)

This involves creating an options object with {} that has a field categories. This field expects a list of all the categories present in this column in ascending order. “Smaller” elements first.

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Done!

Now, we click “Run” in the lower right corner to save. We can now see that our variable Size has a sorting icon next to it, allowing us to sort the whole table.