python - How to compare a numpy array with a scalar? -


this question may seem basic it's generating big mess.

i try compare numpy.array scalar as:

a=numpy.array([0.,1.,2.,-1.,-4.]) if a.any()>0.:     print 'a:',a 

as expected get:

a: [ 0.  1.  2. -1. -4.] 

now if same find negative values

a=numpy.array([0.,1.,2.,-1.,-4.]) if a.any()<0.:     print 'a:',a 

i don't means values greater 0.

its because of a.any returns true (it returns true of 1 of elements meets condition , false in otherwise).and since true , 1 same objects in python (true==1) ,your condition interpreted 1<0 python, false!

>>> true<0 false >>> a.any()<0. false 

and instead of need (a<0).any()

>>> (a<0).any() true 

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