Regarding your second point, you can use the walrus operator to retain the results of a computation within a single `.with_columns()` call. See https://stackoverflow.com/a/77609494

Edited to add: also, if you’re using a lazy dataframe, you can just naively do the same operation twice (once to store it in a named column and once again in the subsequent computation), and Polars will use common subexpression elimination (CSE) to prevent recomputing the result. You can verify this is true using the `.explain()` method of a lazy dataframe operation containing the `.with_columns()` call.