Calling a function with unknown number of parameters Python

Question

I am trying to read in a Fuzzy plain text rule and pass the parameters to a SciKit-Fuzzy function call to create fuzzy rules. For example, if I read in this text rule:

IF service IS poor OR food IS rancid THEN tip IS cheap

Then the function call will be:

ctrl.Rule(service ['poor'] | food ['rancid '], tip ['cheap'])

If text rule is:

IF service IS good THEN tip IS average; 

Then the function call will be:

ctrl.Rule(service ['good '] , tip ['average'])

Since each rule can have unlimited number of input variables, e.g. the user can also say:

IF service IS good AND food IS good AND mood IS happy THEN tip IS high

which contains 3 inputs variables service['good'],food['good'],and mood['happy'], and 1 output variable tip['high']. I can't think of a way to automatically read in the text rule and convert it to a function call, do you have any idea or suggestion to achieve this goal? Any help will be appreciated. Thanks.

Creodont

Does this answer your question? Mini-languages in Python – Aleenaleetha

Answer 1

You could try something like this:

string_input = "IF service IS poor OR food IS rancid THEN tip IS cheap"
string_input = string_input.replace(" THEN ", '"], ').replace(' IS ', '["').strip("IF ").replace(" OR ", '"] | ') +'"]'
eval('ctrl.Rule({})'.format(string_input))

But be warned you need to be very very careful with eval. It is a security risk because user can execute code this way!!! Before using this you might to do research on how to prevent this security issue.

Pulmonary

This eval() function can solve my problem perfectly. Thanks – Creodont

Glad I could help, but as mentioned be aware of potential safety issues if you are considering that user will write that input! Happy Coding! – Pulmonary