Dealing with a dataset with a mix of continuous and categorical variables
To clarify, you mean mixed variables in one column? e.g. ABC123

If yes, you create two additional columns: one with categorical and one with numerical values. Afterward, you can encode them (one hot encoding not always necessary). 

Detailed explanation in Chapter 11 "Feature Engineering Mixed Variables":

https://www.udemy.com/feature-engineering-for-machine-learning/learn/v4/content