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Easier way to retrieve matrix columns or rows? #230

@whitews

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@whitews

Hi Jos,

Thanks for providing such a useful math library for JS. I'm considering MathJS for a current project, and would like some guidance retrieving rows and columns from a Matrix object. Let's say I have a matrix:

var my_matrix = math.matrix(
    [
        [ 0.50, 0.25, 0.00], 
        [ 0.25, 0.50, 1.00]
    ]
);

And, now I want to retrieve the last column as a 1-D array. After trying various approaches, I came up with this:

var super_special_column = math.flatten(
    my_matrix.subset(
        math.index([0, 2], 2)
    )
).toArray();

Admittedly, I may be spoiled from Python's NumPy syntax, but this seems like a lot of work. Is this the easiest/best way to access members of a Matrix in MathJS?

Thanks again,
Scott

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