ben.bighair schrieb:
> On Feb 11, 11:14 am, mort canty <m.ca...@fz-juelich.de> wrote:
>> Hi all,
>>
>> Given a 2-D array such as
>>
>> 0 1 1 2 1
>> 0 2 1 1 1
>> 1 0 2 2 1
>>
>> where the entries are labels, the columns represent items and the rows
>> are voters, I want a IDL function that returns the majority vote labels.
>> So here I should get
>>
>> 0 ? 1 2 1
>>
>> as output, where ? = "don't care". There must _not_ be a loop over
>> columns. I've got a clumsy solution, but I'm sure there's an elegant one
>> somewhere?
>
> Hi,
>
> This is incomplete as it doesn't flag the "don't care" crowd. I can't
> noodle that part out without column looping. Looping would make it
> easy to use something like...
>
> for i = 0, ncol-1 do dontCare[i] = ARRAY_EQUAL(votes[i,*],votes[i,0])
>
> but by your rules, that is out of bounds.
>
> ***BEGIN
> x=[[0,1,1,2,1],$
> [0,2,1,1,1],$
> [1,0,2,2,1]]
> sz = SIZE(x, /DIM)
> votes = [[TOTAL(x EQ 0, 2)],$
> [TOTAL(x EQ 1, 2)], $
> [TOTAL(x EQ 2, 2)]]
> mx = MAX(votes, mxIdx,dim = 2)
> majority = (array_indices(sz, mxIdx, /dim))[1,*]
> print, majority
> ***END
>
>
> Cheers,
> Ben
>
Thanks Ben. What I meant by "don't care" is that I don't care which of
the labels that got equal votes is output. I think my solution is
essentially the same as yours, certainly not more elegant:
function majority_vote, A, num_labels
n = n_elements(A[*,0])
B = intarr(n,num_labels)
for i=0,num_labels-1 do begin
C = A*0
idx = where(A eq i,count)
if count gt 0 then C[idx] = 1
B[*,i] = total(C,2)
endfor
void = max(B,labels,dimension=2)
return, labels/n
end
I was probably hoping for some HISTOGRAM magic :-)
Mort
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