[Numpy-discussion] Computing the norm of an array of vectors

Robert Kern robert.kern@gmail....
Tue Feb 8 11:57:30 CST 2011


On Tue, Feb 8, 2011 at 11:55, Ben Gamari <bgamari.foss@gmail.com> wrote:
> On Tue, 8 Feb 2011 10:46:34 -0600, Robert Kern <robert.kern@gmail.com> wrote:
>> (v*v).sum(axis=1)[:,np.newaxis]
>>
>> You can leave off the newaxis bit if you don't really need a column vector.
>>
> Fair enough, I unfortunately neglected to mention that I ultimately want
> to normalize these vectors, hence the *ones(3) in my original proposal
> (although looking back, the shapes would clearly be incompatible). Is
> there an elegant way to achieve this?

v / np.hypot.reduce(v, axis=1)[:,np.newaxis]

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco


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