Evaluating a mathematical [removed]function) for a large number of input values fast

Question

The following questions

• Evaluating a mathematical expression in a string
  
• Equation parsing in Python
  
• Safe way to parse user-supplied

Answer 1

Since you asked about asteval, there is a way to use it and get faster results:

aeval = Interpreter()
time_start = time.time()
expr = aeval.parse(userinput_function)
for item in database_xy:
    aeval.symtable['x'] = item['x']
    item['y_aeval'] = aeval.run(expr)
time_end = time.time()

That is, you can first parse ("pre-compile") the user input function, and then insert each new value of x into the symbol table and the use Interpreter.run() to evaluate the compiled expression for that value. On your scale, I think this will get you close to 0.5 seconds.

If you are willing to use numpy, a hybrid solution:

aeval = Interpreter()
time_start = time.time()
expr = aeval.parse(userinput_function)
x = numpy.array([item['x'] for item in database_xy])
aeval.symtable['x'] = x
y = aeval.run(expr)
time_end = time.time()

should be much faster, and comparable in run time to using numexpr.