Empty ALE Plot

[hockshem]

Hello,

I am working an XAI research with the popular Portugese banking dataset from UCI ML repo, and I am trying to plot a first-order ALE plot for a single continuous column called pdays.

The distribution of the data is highly skewed, where the 25%, 50%, and 75% quantile all correspond to the same value.

I understand that in this case, the default number of bins will only be 1 because there are only two unique values from the quantiles. However, I cannot entirely comprehend when the resulting plot is empty.

Is this due to the subtraction of the mean differences at the last step (centering the mean effects)? Please correct me if I was wrong.

Sorry for the trouble and I really appreciate your guidance on this.

Thank you in advance!