MATLAB: Is the result of the logical indexing smaller than the original vector

indexinglogical?MATLABsize;

I have a vector "x" and a logical indexing vector "idx", which is the same size as "x". However, when I index into "x" using "idx", the result is a different size.

Why does this happen?

Best Answer

Logical indexing in MATLAB only returns values for the locations where indexing vector is 1, any other values from the original vector are ignored.

To acquire a result of the same size of "x" and "idx", you can consider using the "element-wise multiplication" operator ( .* ), or the "logical and" operator ( & ). For more information, please refer to the following documentation page on Matrix Indexing:

https://www.mathworks.com/help/matlab/math/matrix-indexing.html#bq7egb6-1

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MATLAB: How do you find and replace rows in two tables with some variables in common

Use the "outerjoin" function to find the indices of the match.

https://www.mathworks.com/help/matlab/ref/outerjoin.html#btx2ndz-5

>> [C,ia,ib] = outerjoin(A, B, 'Keys', [2:3], 'MergeKeys', true, 'Type', 'right');

"ia" and "ib" show where each of the table rows in "C", come from in tables "A" and "B". A zero in "ia" indicates that that row in table "C" does not appear in table "A". Use these indices to find the indices in tables "A" and "B" where "ia" is not zero and then find the values at those indices in "ia" and "ib".

>> inda = find(ia~=0);
>> indb = ib(inda);

Those give the correlated indices in tables "A" and "B" that need to be switched.

Then, you can use those indices to index into the "B" table and replace it with the values you obtain by indexing into the "A" table.

>> B(indb,1)=A(ia(inda),1);

MATLAB: How to use Excellink functions in a Excel Macro Function instead of a Sub

The above Macro Subroutine can be translated to the following Macro Function:

Function Calculate(A As Range, b As Range) As Variant
    MLOpen
    MLPutMatrix "A", A
    MLPutMatrix "b", b
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Note Excel Macro Functions only support one output range. For MATLAB functions with multiple outputs, consider writing to multiple ranges directly.

      MLGetMatrix "x", "x"
      MLGetMatrix "y", "y"

Best Answer

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MATLAB: How do you find and replace rows in two tables with some variables in common

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