Matrix Element Transfer from one matrix to another

Question

Ken 2016-10-6

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https://ww2.mathworks.cn/matlabcentral/answers/305964-matrix-element-transfer-from-one-matrix-to-another

评论： Star Strider 2016-10-6

I have a matrix of 10X10. I want to select elements of this matrix and put them in an N X 2 Matrix. As example, if one of the selected elements of the 10X10 matrix is at 10, 12 I want this 10,12 to be transferred to the N X 2 matrix. Hence, basically the question I am asking is how to transfer position i.e row,col of a matrix from one to the other.

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Answer 1

James Tursa 2016-10-6

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I am not quite clear what you are asking. Is it something like this?

>> A = reshape(1:100,10,10)  % <-- test data
A =
     1    11    21    31    41    51    61    71    81    91
     2    12    22    32    42    52    62    72    82    92
     3    13    23    33    43    53    63    73    83    93
     4    14    24    34    44    54    64    74    84    94
     5    15    25    35    45    55    65    75    85    95
     6    16    26    36    46    56    66    76    86    96
     7    17    27    37    47    57    67    77    87    97
     8    18    28    38    48    58    68    78    88    98
     9    19    29    39    49    59    69    79    89    99
    10    20    30    40    50    60    70    80    90   100
>> [row,col] = find(A==47)  % <-- pick off row & column of location of 47
row =
     7
col =
     5
>> B(1,1:2) = [row,col]  % Stuff the row & col into the 1st row of B
B =
     7     5
>> [row,col] = find(A==59)  % <-- pick off row & column of location of 59
row =
     9
col =
     6
>> B(2,1:2) = [row,col]  % Stuff the row & col into the 2nd row of B
B =
     7     5
     9     6

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James Tursa 2016-10-6

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Does this do what you want?

>> A = reshape(randperm(25),5,5)
A =
      17     2    24    14     8
       1    23    16    10     4
      11    12    20    18    15
       6     9    22    13     5
      25     3    21    19     7
>> [row,col] = find(A<10);  % <-- find where A is less than 10
>> result = [row col]
result =
       2     1
       4     1
       1     2
       4     2
       5     2
       1     5
       2     5
       4     5
       5     5

Ken 2016-10-6

Thanks. To try another problem - how to find the steepest -ve gradient from A(1,1) to A(5,5)?

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Answer 2

Star Strider 2016-10-6

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https://ww2.mathworks.cn/matlabcentral/answers/305964-matrix-element-transfer-from-one-matrix-to-another#answer_237632

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If I understand what you want, the find function will do exactly that.

Example:

M = randi(9, 10);                               % Create Matrix
[row,col] = find(M == 3);                       % Return Rows & Cols Of All ‘3’ Values

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Ken 2016-10-6

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I have to find the steepest path from start to destination, but can't do it directly as there are obstacles in the grid (denoted by 1) which I can't traverse. I tried the foll. but OptimalPath is not being printed and I get it wrong:

OptimalPath=zeros(20, 2);

iter=0; Index_OptimalPath=[3,7]; Min=SearchSolution(3,7);

while (Row < 8 & Col < 7)

 while not(SearchSolution(Row,Col) == 1)
   while not(SearchSolution(Row,Col) == 0)
  iter = iter+1;
    assert(maxIter>iter, 'maxIter assert triggered. Aborting.');
 for X=1:1:3
  for Y=1:1:3
   if Min>SearchSolution(SearchStart(1+X),SearchStart(2+Y));
     Min=SearchSolution(SearchStart(1+X),SearchStart(2+Y));
   end
  end
 end
OptimalPath
end
end
Row=Row+1;
Col=Col+1; 
   end