Combine two matrices (100 x 1), then find data corresponding to specific rows?

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Paul 2013-10-8

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评论： Paul 2013-10-8

So I have two matrices, each one (100 x 1).

They are equal in regards to their columns and rows, so I'm assuming that saves some headaches. I need to combine them so I can look up requirements in let's say column A, so I can get the corresponding value from column B.

How would I go about combining the two so I can look up values in one to get the corresponding information from the other column in the same row? I want the final matrix two be 100 x 2 , one column being matrix A values, and the second column being matrix B values. Thank you.

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Answer 1

Image Analyst 2013-10-8

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https://ww2.mathworks.cn/matlabcentral/answers/89478-combine-two-matrices-100-x-1-then-find-data-corresponding-to-specific-rows#answer_98926

在 MATLAB Online 中打开

rowsToExtract = (some expression giving a logical vector)
extractedRows = [A(rowsToExtract ), B(rowsToExtract);

For a concrete example:

% Create data
A = randi(9, 100, 1);
B = randi(9, 100, 1);
% Create the selection criteria:
rowsToExtract = A>=8
% Get values from both A and B in a single array
% that meet the criteria.
extractedRows = [A(rowsToExtract ), B(rowsToExtract)]

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Paul 2013-10-8

Thank you once again!

How would I go about extracting data from one column based on the criteria of the other column.

For example, in column A, I have a few NaN values, after setting up my own criteria for this column. Column B has a its own values from randn values.

I now want to calculate the average of column B, but only rows that have a corresponding value in column A. Thus, if any value in column B corresponds to a NaN value in column A, I want to exclude that value from my average.

I'm tinkering around with the find function, but no luck yet.

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