How to trim data from a double variable?

2013 3 31
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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 =
6 2 1 5 2 6 8 3 2 4
6 8 5 7 6 6 8 5 6 5
7 5 2 5 6 1 5 6 3 7
9 8 2 5 4 9 2 1 9 8
9 2 2 5 2 7 4 8 2 1
7 5 2 2 9 7 2 6 9 2
6 6 2 5 1 1 1 8 5 4
9 1 1 8 1 8 9 4 7 1
6 6 6 8 2 9 3 5 9 5
1 4 3 3 2 9 3 1 3 4
i want an output as following:
output=
6 2 5 2 8 3 4
6 8 7 6 8 5 5
*7 5 5 6 5 6 7*
9 8 5 4 2 1 8
9 2 5 2 4 8 1
7 5 2 9 2 6 2
6 6 5 1 1 8 4
9 1 8 1 9 4 1
6 6 8 2 3 5 5
1 4 3 2 3 1 4
hope this clarifies it.

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Image Analyst
Image Analyst 2013-3-31
How is the output 7 by 10 if you're only operating on row 3? Do you want to do all rows? If so, and there are different numbers of elements in each row that meet the criteria (e.g. 7 for one row but 3 for another row, etc.) then you'll have to use a cell array.
Umesh
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
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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Image Analyst
Image Analyst 2013-3-31
编辑：Image Analyst 2013-3-31

2 个投票

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

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Umesh
Umesh 2013-3-31
it gives out put as double<1x7>. It doesn't extend for other rows.
Walter Roberson
Walter Roberson 2013-3-31
You have not defined what values you want to have in the output when there are fewer than 10 "valid" numbers in a row ?
Image Analyst
Image Analyst 2013-3-31
I don't understand what you want. For the sample fullArray2D array I gave above, please give your full desired output.
Umesh
Umesh 2013-3-31
i was able to figure out solution to this problem. anyways thank you all!
Image Analyst
Image Analyst 2013-3-31
That's good because I haven't the slightest idea how you got your output in your "clarification" above.
Umesh
Umesh 2013-3-31
now you should check it again...my bad, i made a mistake.
Image Analyst
Image Analyst 2013-3-31
This is how I'd do it.
% 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:
output = fullArray2D(:, columnsMatchingCriteria)
This gives the original 2D array with columns excluded if the conditions for row 3 are not met.
Umesh
Umesh 2013-3-31
Yeah! It works. thank you!!
Image Analyst
Image Analyst 2013-3-31
Mark the answer as "Accepted" then. Thanks.

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