Python equivalence to inline functions or macros

user_621944 0
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I just realized that doing

x.real*x.real+x.imag*x.imag

is three times faster than doing

abs(x)**2

where x is a numpy array of complex numbers. For code readability, I could define a function like

def abs2(x):
    return x.real*x.real+x.imag*x.imag

which is still far faster than abs(x)**2, but it is at the cost of a function call. Is it possible to inline such a function, as I would do in C using macro or using inline keyword?

inline-functions optimization python
6 Answers

Not exactly what the OP has asked for, but close:

Inliner inlines Python function calls. Proof of concept for this blog post

from inliner import inline

@inline
def add_stuff(x, y):
    return x + y

def add_lots_of_numbers():
    results = []
    for i in xrange(10):
         results.append(add_stuff(i, i+1))

In the above code the add_lots_of_numbers function is converted into this:

def add_lots_of_numbers():
    results = []
    for i in xrange(10):
         results.append(i + i + 1)

Also anyone interested in this question and the complications involved in implementing such optimizer in CPython, might also want to have a look at:

user_27057570

You can try to use lambda:

abs2 = lambda x : x.real*x.real+x.imag*x.imag

then call it by:

y = abs2(x)
user_76961390
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