If one value in a column is overrepresented, you might think it’s the only value present since Polars displays only the first five and last five rows of the dataframe. To see the different kinds of values in a column, you need to ensure that each value is shown only once. Below is a dataframe showing cereal brands.
shape: (77, 2)
manufacturer
type
str
str
"Nabisco"
"Cold"
"Quaker Oats"
"Cold"
"Kellogs"
"Cold"
"Kellogs"
"Cold"
"Ralston Purina"
"Cold"
…
…
"General Mills"
"Cold"
"General Mills"
"Cold"
"Ralston Purina"
"Cold"
"General Mills"
"Cold"
"General Mills"
"Cold"
Show each value once
Say you want to see all the different types of cereal, you can select the type column and use the unique method to display each value only once like this:
(df .select('type') .unique() )
shape: (2, 1)
type
str
"Cold"
"Hot"
Now you can see that there are two types of cereal in this dataset: cold and hot.