How to apply a matlab code on a matrix if it already working on column vector.

Question

M.S. Khan 2019-8-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474842-how-to-apply-a-matlab-code-on-a-matrix-if-it-already-working-on-column-vector

评论： M.S. Khan 2019-8-13

MM = [3 3 3; 3 3 3; 0 0 0;0 0 0;3 3 3;3 3 3;0 0 0;0 0 0;0 0 0;3 3 0;0 3 3;0 0 3;3 0 0;3 3 0;3 3 3;0 0 0; 0 0 0;3 3 3;0 0 0];

i want to get output matrix in this shape:

output=[3 3 3;3 3 3;3 3 3;3 3 3 ;3 3 3;3 3 3;4 4 4;4 4 4;4 4 4;3 3 4;4 3 3;4 4 3;3 4 4;3 3 4;3 3 3;3 3 3;3 3 3;3 3 3;0 0 0];

% --------------------------------------------------------------
% This coding is working nicely on a column vector M. 
% How to apply it on a matrix MM as given above. 
%--------------------------------------------------------------
M =[3,3,0,0,3,3,0,0,0,3,3,0,0,3,3,0,0,3,0]';
m = M;
m(m == 0) = nan;
%lo - define the indices of the values that need to be changed: 
lo = fillmissing(m,'previous') == 3 & fillmissing(m,'next') == 3 & isnan(m); 
% ii - assign numbers to intervals:
ii = cumsum([0;diff(lo)>0]).*lo; 
%{
p - count the amount of each value of vector ii:
1 element -  the number of zeros (0's);
2 element the number of values in the first interval.
3 element the number of values in the second interval, etc.:
%}
p = accumarray(ii(:)+1,1);
% Let a - the values for to be changed (vector with length equal max(ii), in our case - 4):
a = [3,4,4,3]'; % HERE fixed..
% Condition for intervals with length equal 1
a(p == 1) = 3;
% Replacement:
M(lo) = a(ii(lo));

Thanks for all cooperation.

Very thankful for support in advance.

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KSSV 2019-8-5

What is the criteria to replace some zeros with 3 and others with 4?

M.S. Khan 2019-8-5

If we compare M and output matrix.

suppose its a column vector: [3 00 3 0003 0003 00030]' => [3 3 3 3 4 4 4 3 4 4 4 3 3 3 3 3 0]'

pattern of filling:

-- Between first and next 3, repalce 0s with 4

-- Beteeen next 3 and next coming 3, replace 0s with 4

-- next 3 and next coming 3, replace 0s with 3

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Answer 1

Andrei Bobrov 2019-8-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474842-how-to-apply-a-matlab-code-on-a-matrix-if-it-already-working-on-column-vector#answer_387259

编辑：Andrei Bobrov 2019-8-12

在 MATLAB Online 中打开

[r,c] = size(MM);
m = MM;
m(m == 0) = nan;
%lo -define the indices of the values that need to be changed: 
lo = fillmissing(m,'previous') == 3...
                      & fillmissing(m,'next') == 3 & isnan(m); 
% ii - assign numbers to intervals:
ii = cumsum([zeros(1,c);diff(lo)>0]).*lo; 
%{
p - count the amount of each value of vector ii:
1 element -  the number of zeros (0's);
2 element the number of values in the first interval.
3 element the number of values in the second interval, etc.:
%}
[y,x] = ndgrid(1:r,1:c);
p = accumarray([ii(:)+1,x(:)],1);
p = p(2:end,:);
% Let a -the values for to be changed (vector for each column 
% with length equal max(ii), in our case - 4):
a = repmat([3,4,4,3]',1,c);
% Condition for intervals with length equal 1
a(p == 1) = 3;
% Replacement:
MM(lo) = a(ii(lo));

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M.S. Khan 2019-8-13

Thanks Dr. Andrei Bobrov

Really you are great mind. Prayers and good wishes for you.

Warm Regards

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Answer 2

Chidvi Modala 2019-8-8

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/474842-how-to-apply-a-matlab-code-on-a-matrix-if-it-already-working-on-column-vector#answer_386713

I am assuming the length of vector MM is pxq

You can use the below code

for i=1:q 
M=MM(:,i); 
% insert your algorithm here 
M(lo)=a(ii(lo)); 
MM(:,i)=M; 
end 

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M.S. Khan 2019-8-12

for i=1:q ===> what will be the length of q?

M.S. Khan 2019-8-12

在 MATLAB Online 中打开

MM  =  [3  3  3; 3  3  3; 0  0  0;0  0  0;3 3 3;3 3 3;0 0 0;0 0 0;0 0  0;3 3 0;0 3 3;0 0 3;3 0 0;3 3 0;3 3 3;0  0 0; 0 0 0;3 3 3;0 0  0];
q = length(MM)
for i=1:q 
M=MM(:,i); 
m = M;
m(m == 0) = nan;
%lo - define the indices of the values that need to be changed: 
lo = fillmissing(m,'previous') == 3 & fillmissing(m,'next') == 3 & isnan(m); 
% ii - assign numbers to intervals:
ii = cumsum([0;diff(lo)>0]).*lo; 
%{
p - count the amount of each value of vector ii:
1 element -  the number of zeros (0's);
2 element the number of values in the first interval.
3 element the number of values in the second interval, etc.:
%}
p = accumarray(ii(:)+1,1);
% Let a - the values for to be changed (vector with length equal max(ii), in our case - 4):
a = [3,4,4,3]'; % HERE fixed..
% Condition for intervals with length equal 1
a(p == 1) = 3;
% Replacement:
M(lo) = a(ii(lo));
MM(:,i)=M; 
end 
% ----------------------------------- -----------------------
% the lenght of q is undefined. 