| Re: Multi-Array comparison [message #71547] |
Mon, 28 June 2010 08:00  |
Jeremy Bailin
Messages: 618
Registered: April 2008
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Senior Member |
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On Jun 27, 10:57 pm, Jeremy Bailin <astroco...@gmail.com> wrote:
> On Jun 27, 9:40 am, wlandsman <wlands...@gmail.com> wrote:
>
>
>
>
>
>> Here's one way to do what I think you want. (I am not sure what you
>> mean by a "best server".) If your 3 arrays are a,b, and c then
>
>> arrmax = a > b > c ;get the maximum value at each i,j
>> Na = total(a EQ arrmax) ;Number of times the maximum is found in the
>> a array
>> Nb = total(b EQ arrmax)
>> Nc = total(c EQ arrmax)
>
>> Then the maximum of Na, Nb, Nc will tell you which array has the most
>> pixels at the maximum value. (Note that Na + Nb + Nc may be more
>> than the total number of pixels if there are equal values.) --Wayne
>
>> On Jun 27, 4:58 am, Giuseppe Papa <giuseppep...@gmail.com> wrote:
>
>>> Hello everybody,
>
>>> I have three fltarr(460,483) and I would like to compare them, finding
>>> for each element i,j of the arrays which one among the three guarantee
>>> the maximum value. However, since I just need to know a sort of "best
>>> server" index, I'm looking for the percentage so finding the total
>>> amount will be enough. I've found out the WHERE function, but in my
>>> case (three or more arrays) should I make a loop? Any ideas?
>
>>> Thanks,
>
>>> Giuseppe
>
> Or how about:
>
> maxval = max([[[a]],[[b]],[[c]]], dimen=3, ind)
> print, max(histogram(ind / n_elements(a)))
>
> -Jeremy.
Of course, if you already have your storedfiles array set up like
that, susbtitute that for the [[[a]],[[b]],[[c]]] mess. :-)=
I should also point out that, unlike Wayne's code, this one doesn't
attribute equal values to each case where they occur - just to the
first one. So you can construct pathological inputs where it gives the
wrong answer - though if you never or rarely expect to encounter the
same value then you'll never run into it.
-Jeremy.
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