[Tutor] How to sum rows and columns of a matrix?

[Pierre Barbier de Reuille]

Even better :

>>> import numarray
>>> m = numarray.arange(16,shape=(4,4))
>>> numarray.sum(m)
array([24, 28, 32, 36])
>>> numarray.sum(axis=1)
array([ 6, 22, 38, 54])

Pierre

Kent Johnson a écrit :
> Kent Johnson wrote:
> 
>> Liam Clarke wrote:
>>
>>> There's a specific package for arrays
>>> http://www.stsci.edu/resources/software_hardware/numarray
>>>
>>> that implements array mathematics. I use it for pixel map manipulation
>>> in pygame, so it's relatively fast.
>>
>>
>>
>> Here is one way to do what you want using numarray:
> 
> 
> Here is another way, probably more idiomatic and faster. (I'm just 
> doodling with numarray so there may still be a better way to do this...)
> 
>  >>> import numarray
>  >>> m=numarray.array(range(16),shape=(4,4))
> 
>  >>> numarray.add.reduce(m)
> array([24, 28, 32, 36])
> 
>  >>> numarray.add.reduce(m, axis=1)
> array([ 6, 22, 38, 54])
> 
> Kent
> 
>>

-- 
Pierre Barbier de Reuille

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