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indices when the columns are all nan

조회 수: 5(최근 30일)
Sagar 2016년 3월 16일
댓글: Sagar 2016년 3월 17일
I am using [m, d] = nanmax (r_all); to get the maximum values and corresponding indices in matlab. There are several columns in r_all in which all the elements are nans. Unfortunately, nanmax returns '1' in indices for those columns that have all nans. However, there are actual indices that are value '1' so it creates confusion. How can I force matlab to return 'a' or 'b' as the output instead of returning 0' or '1'? Could you please suggest other solutions to this problem?
  댓글 수: 6
Sagar 2016년 3월 16일
attached is the data. Please follow the link:

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채택된 답변

Stephen 2016년 3월 16일
편집: Stephen 2016년 3월 16일
There is no need to waste time using slow and ugly loops and if statements. You can locate those "incorrect" indices very simply using basic MATLAB indexing:
>> mat = [0,1,2,NaN,3,NaN;4,NaN,5,NaN,6,NaN;7,8,NaN,NaN,NaN,9]
mat =
0 1 2 NaN 3 NaN
4 NaN 5 NaN 6 NaN
7 8 NaN NaN NaN 9
>> [m,idx] = nanmax(mat) % max value and its indices
m =
7 8 5 NaN 6 9
idx =
3 3 2 1 2 3
>> idx(all(isnan(mat),1)) = NaN % replace all-NaN indices with NaN
idx =
3 3 2 NaN 2 3
  댓글 수: 3
Sagar 2016년 3월 17일
Thanks Stephen, apparently I didn't know there is 'all' function which I needed. :)

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추가 답변(1개)

KSSV 2016년 3월 16일
clc; clear all ;
load data.mat ;
[m,n] = size(data) ;
idx = zeros(n,1) ;
val = idx ;
% column wise
for c = 1:n
[i,j] = nanmax(data(:,c)) ;
if isnan(i)
j = 50 ;
idx(c) = j ;
val(c) = i ;


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