Symengine .subs is calling back to Python

[peendebak]

When executing the symengine subs on just basic types a callback to the python interpreter is make. A minimal example:

import symengine
x,y=symengine.symbols('x, y')
f=x*x+y*y/2
f.subs({x: 1.0, y: x}) # this triggers __instancecheck__ from abc.py

When profiling the expression (with cProfile + snakeviz) we get:

(the magenta block is the call back to python)

If the call back to the python interpreter can be avoided, the code is more efficient.

[lucienwang1009]

Meet the same issue. Hope it would be fixed.

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PyObject_TypeCheck might be an alternative?

[rikardn]

Thanks for reporting this.

A quick glance at the source makes me guess it is DictBasic that inherits from abc.MutableMapping. Do we have to do this?

There is also the BasicMeta, but it doesn't seem to be used anywhere. Can this be removed?

[isuruf]

This is because we have to check the type of the keys and values of the dictionary and convert all of them to Basic types. If you are re-using the dictionary, then you can create a DictBasic dictionary so that the type checks are not done repeatedly. If you are using the dictionary once, there's very little we can do.