pmf | probabilistic matrix factorization | Recommender System library

The problem is scoping. gam() looks for the variables in formula and offset first in the data argument, then in the environment that's attached to formula. Normally that would be the environment where formula was created; in your example that would be the global environment.

You should be able to get things to work by adding the offset_ variable to the local copy of data, for example

Note that only field-like events can be used in this way:

For what you need to plot, might be easier to provide the bins to make your histogram:

You could use sympy to get an exact answer:

Easy and simple solution:

There is no factorial operation available, but one suitable option might be to approximate it with Stirling's approximation, or perhaps a Stirling series if more accuracy is required.

For example, in Vega-Lite (view in editor):

Your code is very messy and should be cleaned up. When asking the questions here you usually should create a MRE in which the concrete problem is highlighed, instead of pasting your whole code base here and letting us find your bugs.

Anyways since I got interested on this I spent a moment of googling and found your question already answered here.

It says the ORA-01797 is related to the query missing the to_date() constant.

From looking at your code I can see several places where it's missing like the following one:

You have semicolon ";" before your "Where clause". You need to remove it from there to make Oracle take account of both your "Where clause" and your "Order by clause"

You can do following: