How to control number of element or number of unique element in Matrix?

Question

Triveni 2016-2-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/270452-how-to-control-number-of-element-or-number-of-unique-element-in-matrix

评论： Triveni 2016-2-29

x= [15 30 45 60 -45 -30 0 90 15 30 45 60 -45 -30 0 90 15 45 60 -45 -30 0];%Initial guess
 a = unique(x);   % unique elements
 [countingofangles, Thetaangles]  = hist(x,unique(x));   % Unique Theta and counting of theta
  A = Thetaangles;     % Theta used in initial guess x
 c = countingofangles;     %No of theta used in initial guess x
y = repmat(x,numel(a),1);    %repeat x matrix
y(:,end) = a';           %replace last column by transpose(a)

output

 A =
   -45   -30     0    15    30    45    60    90     %Theta used in x
 c =
     3     3     3     3     2     3     3     2     %Number of theta corresponding to A
 y =
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30   -45
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30   -30
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30     0
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30    15
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30    30
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30    45
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30    60
    15    30    45    60   -45   -30     0    90    15    30    45    60   -45   -30     0    90    15    45    60   -45   -30    90

I want to eliminate/delete that row which contains no of theta/counting of theta/angles(15,30, 45 etc) less than 3

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Answer 1

the cyclist 2016-2-28

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https://ww2.mathworks.cn/matlabcentral/answers/270452-how-to-control-number-of-element-or-number-of-unique-element-in-matrix#answer_211551

在 MATLAB Online 中打开

I'm not 100% certain I understand your question, but I think this does what you want:

y(c<3,:) = [];

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Image Analyst 2016-2-29

Generally you would NOT want to throw out bins at various places in the histogram. It would make it very difficult and deceiving to try to use the arrays afterwards.

Triveni 2016-2-29

在 MATLAB Online 中打开

Lot of thanks Sir, Actually i developing an algorithm, that's why i need this type of array. Lastly please help me once again, I have a Matrix.

 y =[ 90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75   -75
         90    90   -45     0     0   -45   -45     0   -45    15    30   -30    75   -45    75   -45
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75   -30
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75     0
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75    15
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75    30
         90    90    45     0     0    45    45     0    45    15    30   -30    75    45    75    45
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75    75
         90    90   -45     0     0    45    45     0   -45    15    30   -30    75   -45    75    90];