[Numpy-discussion] Finding a row match within a numpy array

Andy Cheesman Andy.cheesman@bristol.ac...
Wed Aug 15 05:26:15 CDT 2007


Thanks for the speedy response but where can I locate the find function
as it isn't in numpy.

Andy

mark wrote:
> I think you can create an array with a true value in the right spot as
> folows:
> 
> row = all( equal(a,b), 1 )
> 
> Then you can either find the row (but you already knew that one, as it
> is b)
> 
> a[row]
> 
> or the row index
> 
> find(row==True)
> 
> Mark
> 
> On Aug 15, 11:53 am, Andy Cheesman <Andy.chees...@bristol.ac.uk>
> wrote:
>> Dear nice people
>>
>> I'm trying to match a row (b) within a large numpy array (a). My most
>> successful attempt is below
>>
>> hit = equal(b, a)
>> total_hits = add.reduce(hit, 1)
>> max_hit = argmax(total_hits, 0)
>> answer = a[max_hit]
>>
>> where ...
>> a = array([[ 0,  1,  2,  3],
>>            [ 4,  5,  6,  7],
>>            [ 8,  9, 10, 11],
>>            [12, 13, 14, 15]])
>>
>> b = array([8,  9, 10, 11])
>>
>> I was wondering if people could suggest a possible more efficient route
>> as there seems to be numerous steps.
>>
>> Thanks
>> Andy
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> 
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