Why am I getting this TypeError: quantile() got an unexpected keyword argument 'numeric_only' for pandas quantile()?

Question

I ran into a weird error with pandas quantile() (pandas.DataFrame.quantile()) method. I have a dataframe with both numeric and non-numeric columns. I wanted to calculate the 75th quantile for each numeric column. So instead of providing only the numeric columns, I saw in the documentation that quantile() takes a keyword argument numeric_only which does the job. Here is the link to the documentation. But when I run the quantile() with numeric_only = True, python gives me this error:

TypeError: quantile() got an unexpected keyword argument 'numeric_only'

I also checked the implementation of the quantile() and this keyword argument is implemented. Can anyone explain why am I getting this error? Below is a toy example.

df = pd.DataFrame.from_dict({'a':[1,1,2,1,3,2,4,5,4,6,2,3,2,5,5,5]})
df['a'].quantile(q=0.5,numeric_only=True) # doesn't work
df['a'].quantile(q=0.5) # works

Thanks for your help.

Answer 1

By using df['a'].quantile your are calling the quantile method of a column, i.e. a series. This does not have this parameter ( see here).

Since the series has just one type, it is not required.

Answer 2

The error message you're receiving is because the quantile() method does not accept a numeric_only argument.

The numeric_only argument is applicable for some pandas methods (like mean(), sum(), etc.) that can be applied to a DataFrame which contains both numeric and non-numeric columns. These methods will only be applied to the numeric columns when numeric_only=True.

However, when you are using the quantile() method on a Series (which is what df['a'] is), the numeric_only argument is not applicable since a Series only contains a single set of data and should be of the same data type. If you are applying quantile() on a DataFrame, it will automatically apply the method to the numeric columns only, as non-numeric data does not have a concept of quantiles.