SUB-MATRIX extraction

[Martin P. Hellwig]

Jon Clements wrote:
> On Dec 8, 1:36 pm, Pierre <pierre.gaill... at gmail.com> wrote:
>> Hello,
>>
>> let b = array([ [0,1,2] , [3,4,5] , [6,7,8] ])
>>
>> How can I easily extract the submatrix [ [0 ,1], [3, 4]] ?
>>
>> One possiblity is : b[[0,1],:][:,[0,1]] but it is not really easy !
>>
>> Thanks.
> 
> x = numpy.array([ [0,1,2], [3,4,5], [6,7,8] ])
> print x[0:2,:2]
>>>> array([[0, 1],
>        [3, 4]])
> 
> Check out http://www.scipy.org/Tentative_NumPy_Tutorial
> 
> hth,
> 
> Jon.

Yeah numpy is great like that and is the most obvious and probably the 
most right solution, however I'd like to mention if you are going to do 
a lot of stuff that is going to look an awful lot like SQL, perhaps it 
is easier to pump it in a (in :memory:) sqlite table and use it that 
way. Chances are though that you are far better of with numpy.

-- 
MPH
http://blog.dcuktec.com
'If consumed, best digested with added seasoning to own preference.'