def f(x):
x=x/5.
return x
def g(x):
x/=5.
return x
x_var = np.arange(5,dtype=np.double)
f(x_var)
print x_var
g(x_var)
print x_var
Output:
[ 0. 1. 2. 3. 4.]
[ 0. 0.2 0.4 0.6 0.8]
This behavior is a little bit strange to me, I always thought x/=5. was equivalent to x=x/5. . But clearly the g(x) function does not create a new reference with /= operation. Could anyone offer an explanation for this?
Best answer
I always thought x/=5. was equivalent to x=x/5
It is, unless the class overrides the __idiv__ operator, like numpy.ndarray does.
numpy.ndarray overrides it to modify the array in-place, which is good because it avoids creating a new copy of the array, when copying is not required. As you can guess, it also overrides the rest of the __i*__ operators.