How to trim data from a double variable?

Question

Umesh 2013-3-31

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/69302-how-to-trim-data-from-a-double-variable

Lets say we have a double variable 10x10 array, and entries in its 3rd row are (1,2,5,6,5,6,7,8,2,4), we need the values corresponding to data between 4 and 8 for this row, i.e. there are 7 valid entries in this row so we need the final output as a double variable 10x7 only. Thank you in advance!

let me clarify it with example: fullArray2D =

   2     1     5     2     6     8     3     2     4
   8     5     7     6     6     8     5     6     5
   5     2     5     6     1     5     6     3     7
   8     2     5     4     9     2     1     9     8
   2     2     5     2     7     4     8     2     1
   5     2     2     9     7     2     6     9     2
   6     2     5     1     1     1     8     5     4
   1     1     8     1     8     9     4     7     1
   6     6     8     2     9     3     5     9     5
   4     3     3     2     9     3     1     3     4
i want an output as following:
output=
   2     5     2       8     3       4
   8     7     6       8     5       5
    *7     5     5     6       5     6       7*
   8     5     4       2     1       8
   2     5     2       4     8       1
   5     2     9       2     6       2
   6     5     1       1     8       4
   1     8     1       9     4       1
   6     8     2       3     5       5
   4     3     2       3     1       4
hope this clarifies it.

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Umesh 2013-3-31

sorry there was a glitch in there, i wanted an output of dimension 10x7. I want to operate on row three and extend it for corresponding column.

Image Analyst 2013-3-31

When you're operating on row 3 (a row vector of 10 elements), what does "the corresponding column" mean (corresponding to what?), and what does "extend it" mean?

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Answer 1

Image Analyst 2013-3-31

2
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/69302-how-to-trim-data-from-a-double-variable#answer_80543

编辑：Image Analyst 2013-3-31

在 MATLAB Online 中打开

Try this:

% Extract row #3 only from the full 2D array:
row3 = = fullArray2D(3, :);
% Find columns meeting our criteria:
columnsMatchingCriteria = row3>4 & row3<8; % A logical array
% Now extract those elements meeting the criteria:
extractedElements = row3(columnsMatchingCriteria);

If there are different numbers and you need it for each row, then:

fullArray2D = randi(9, 10,10)
for row = 1 : size(fullArray2D, 1)
  % Extract row #3 only from the full 2D array:
  thisRow = fullArray2D(row, :);
  % Find columns meeting our criteria:
  columnsMatchingCriteria = thisRow>4 & thisRow<8; % A logical array
  % Now extract those elements meeting the criteria:
  validNumbers = thisRow(columnsMatchingCriteria);
  % Print out to command window.
  fprintf('There are %d valid numbers for row #%d are: ', length(validNumbers), row);
  fprintf('%d ', validNumbers);
  fprintf('\n');
  % Store in cell array.  Need cell array because length(validNumbers)
  % might tbe different for different rows.
  extractedElements{row} = validNumbers;
end

In the command window:

fullArray2D =
     5     6     4     9     3     3     5     1     9     8
     5     7     2     4     1     5     6     6     5     8
     8     4     3     1     2     9     3     3     7     4
     4     6     3     4     7     7     2     9     6     6
     5     8     3     7     7     8     5     9     1     8
     9     1     2     8     8     4     4     3     5     9
     1     1     4     5     6     5     8     8     6     7
     9     9     2     7     1     6     8     9     5     2
     2     6     8     9     9     3     7     6     4     6
     7     3     1     1     8     7     2     8     9     1
There are 3 valid numbers for row #1 are: 5 6 5 
There are 6 valid numbers for row #2 are: 5 7 5 6 6 5 
There are 1 valid numbers for row #3 are: 7 
There are 5 valid numbers for row #4 are: 6 7 7 6 6 
There are 4 valid numbers for row #5 are: 5 7 7 5 
There are 1 valid numbers for row #6 are: 5 
There are 5 valid numbers for row #7 are: 5 6 5 6 7 
There are 3 valid numbers for row #8 are: 7 6 5 
There are 4 valid numbers for row #9 are: 6 7 6 6 
There are 2 valid numbers for row #10 are: 7 7