MATLAB: All negative number on bottom

matrixsort

How i can sort matrix of numbers and put negative on bottom respecting the order of positive elements.

A = [1,-3,4;-2,5,6;4,2,1]
newA = [1,5,4;4,2,6;-2,-3,1]

Best Answer

>> A = [1,-3,4;-2,5,6;4,2,1]
A =
   1  -3   4
  -2   5   6
   4   2   1
>> S = size(A);
>> [~,R] = sort(A<0,1);
>> C = ones(S(1),1)*(1:S(2));
>> X = sub2ind(S,R,C);
>> A(X)
ans =
   1   5   4
   4   2   6
  -2  -3   1

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MATLAB: How to add value at end of row in a matrix

Without any loops:

R = [2;4;5;2];
C = [1;3;6;7];
[~,X] = sort(R);
[~,~,Y] = unique(R);
Z = accumarray(Y,ones(size(R)),[],@(v){v});
Y(X) = cell2mat(cellfun(@cumsum,Z,'UniformOutput',false));
A = zeros(max(R),max(Y));
A(sub2ind(size(A),R,Y)) = C

creates this output:

MATLAB: Hello, how can i remove zero from an array and leave the array in the same form? thanks

Edit 20170214: added comments as requested

>> A = [1,0,2,6,0;0,3,4,0,0;5,0,2,7,4]
A =
   1     0     2     6     0
   0     3     4     0     0
   5     0     2     7     4
>> S = size(A);
% sort the zero elements of A to be last, C contains the column indices of the sorted data:
>> [~,C] = sort(A==0,2);
% define row indices:
>> R = repmat((1:S(1)).',1,S(2));
% use the row and (sorted) column indices to create linear indices, sort A using the linear indices:
>> B = A(sub2ind(S,R,C));
% remove all columns that contain only zeros:
>> B(:,all(B==0,1)) = [];
% replace zeros with NaN:
>> B(B==0) = NaN
B =
   1     2     6   NaN
   3     4   NaN   NaN
   5     2     7     4

Best Answer

Related Solutions

MATLAB: How to add value at end of row in a matrix

MATLAB: Hello, how can i remove zero from an array and leave the array in the same form? thanks

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