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Python treasures from the internet

My collection of interesting posts on python.

Local and global variables in functions

Using global variables to local functions can be dangerous! Example the code below:

beta = 10
alfa = list(np.arange(1, 5))
for j in np.arange(0, 3):
    def xx(j, beta, alfa):
        beta = beta * (1+j*1e-4)
        alfa[1] = 1232342.+j
        print(f'     inside     : {j=} {beta=:<12.3f}, {alfa=}')
    print(f' in the main    : {j=} {beta=:<12.3f}, {alfa=}')
    xx(j, beta, alfa)
    print(f' >> final : {beta=:<12.3f}, {alfa=}')
which produces this output: 
    in the main    : j=0 beta=10.000      , alfa=[1, 2, 3, 4]
        inside     : j=0 beta=10.000      , alfa=[1, 1232342.0, 3, 4]
    >> final : beta=10.000      , alfa=[1, 1232342.0, 3, 4]
    in the main    : j=1 beta=10.000      , alfa=[1, 1232342.0, 3, 4]
        inside     : j=1 beta=10.001      , alfa=[1, 1232343.0, 3, 4]
    >> final : beta=10.000      , alfa=[1, 1232343.0, 3, 4]
    in the main    : j=2 beta=10.000      , alfa=[1, 1232343.0, 3, 4]
        inside     : j=2 beta=10.002      , alfa=[1, 1232344.0, 3, 4]
    >> final : beta=10.000      , alfa=[1, 1232344.0, 3, 4]
So, the variable beta is used inside the function but is not modified outside its scope, while the object alfa is modified for the whole program.

A good reading on the issue here