Partial Piercing Evaluation

Question

I need to take a formula that uses the OpenDocument formula syntax, analyze it in a syntax that Python can understand, but without evaluating the variables, and then be able to repeatedly evaluate the formula when changing the values ​​for the variables. Formulas can be entered by the user, so pyparsing allows me to effectively handle formula syntax and clean user input. There are a number of good examples of pyration, but all mathematical ones seem to suggest that everyone immediately evaluates everything in the current area.

In the context, I work with a model of an industrial economy (life cycle assessment or LCA), where these formulas represent the volume of material or energy exchanges between processes. A variable amount can be a function of several parameters, such as geographic location. The formula chain and variable references are stored in a directed acyclic graph, so that formulas can always be easily evaluated. Formulas are stored as rows in the database. My questions:

• Is it possible to analyze the formula so that the analyzed estimate can also be stored in the database (as a string to be reset to zero or something else)?
• Are there alternatives to this approach? Keep in mind that the ideal solution is to parse / write once and read many times. For example, by partially analyzing the formula and then using the ast module, although I do not know how this could work with the database repository.
• Any examples of a project or library like this that I could browse? I am not a programmer, just a student who is trying to finish his dissertation, while in his free time he is developing an open source LCA software model.
• Is this approach too slow? I would like to be able to make significant Monte Carlo runs, where each run can include tens of thousands of formula evaluations (this is a large database).

Answer 1

1) , . , , .

2) , eval, :

>>> y = compile("m*x+b","","eval")
>>> m = 100
>>> x = 5
>>> b = 1
>>> eval(y)
501

, eval exec, , . , .

3) - "" wiki. simpleBool.py evalArith.py, , , 2008 . Python, " " / Pyparsing " , , .

4) , , - . . . MC , , . , , memoize , / .

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