We can import numpy and use its functions directly as:
from numpy import *
a = arraay([1,2,3]) # and it works well.
Why do some people use the following method?
import numpy as np
a= np.array([1,2,3])
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4Take a look at https://stackoverflow.com/questions/2386714/why-is-import-bad – Warren Weckesser Jan 10 '18 at 21:17
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The second import is better in case some libraries have the same function names -- it keeps the namespaces separate and clear. – rmilletich Jan 10 '18 at 21:19
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The difference is easy: from numpy import * imports all names from the top-level NumPy module into your current "module" (namespace). import numpy as np will just make that top-level NumPy module available if you use np.xxx.
However there is one reason why you shouldn't use from any_module import *: It may just overwrite existing names. For example NumPy has its own any, max, all and min functions, which will happily shadow the built-in Python any, max, ... functions (a very common "gotcha").
My advise: Avoid from numpy import * even if it seems like less effort than typing np. all the time!
MSeifert
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It's a matter of neatness but also consistency: you might have multiple functions with the same name from different modules (for instance there's a function called "random" in Numpy, but also in other packages like SciPy) so it's important to denote which exact function you're using from which exact module. This link has a great explanation and makes the point about code readability as well.
neophlegm
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