MATLAB: How replace the duplicated row by the mean

machine learningstatisticsStatistics and Machine Learning Toolbox

Hi,

I have below data:

1.3
1.5
1.6
1.7
1.7
2.2
2.8
2.8

I want to find the row index of duplicate values (row4 & row5, row row7& row8) and replace these row by mean 1. row4&row5 replace by the average of them, similarly row7&row8

the final output is:

1.3
1.5
1.6
1.7
2.2
2.8

Best Answer

Assuming that there is more to your question, and that your input is actually a matrix where one of the column has got the indexing values you mention:

[~, ~, group] = unique(yourmatrix(:, idcolumn), 'stable'); 
newmatrix = splitapply(@(rows) mean(rows, 1), yourmatrix, group)

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MATLAB: Average Multiple Matrix Columns Based On Duplicate Entries In A Different ColumnVector

So if I understood correctly, the shape of B does not matter and it is to be considered a column vector.

[~, ~, subs] = unique(A, 'stable');
C = accumarray(subs, B(:), [], @mean)

Note that whether or not the groups appear only once does not matter for the above. All the values with the same corresponding A still get averaged.

Also note that if A is already integer values from 1 to n with no gap and in the right order, then the call to unique is unnecessary and you can just pass A instead of subs.

MATLAB: How can I reshape vector data into a matrix

How do I reshape this to make the 3rd column into a 2x2 matrix, so that the whole thing can be graphed as a surface?

You don't, it's completely unnecessary

surf(yourmatrix(:, 1), yourmatrix(:, 2), yourmatrix(:, 3));

If you wanted to do the reshape (which again is completely unnecessary), and assuming that the X and Y coordinates that are supposed to be identical are actually identical down to the last binary digit, then:

[~, ~, col] = unique(yourmatrix(:, 1));
[~, ~, row] = unique(yourmatrix(:, 2));
X(row, col) = yourmatrix(:, 1);
Y(row, col) = yourmatrix(:, 2);
Z(row, col) = yourmatrix(:, 3);

Best Answer

Related Solutions

MATLAB: Average Multiple Matrix Columns Based On Duplicate Entries In A Different ColumnVector

MATLAB: How can I reshape vector data into a matrix

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