MATLAB: I cannot modify the ‘FaceAlpha’ property of the ‘Rectangle’ object

facealphaMATLABrectangle

When I create a rectangle using:

>> a=annotation('rectangle')

I can modify its 'FaceAlpha' property. However, when I create it using:

>> b=rectangle();

then there is no 'FaceAlpha' value for me to modify even though both "a" and "b" are shown as 'Rectangle' objects.

Best Answer

While both "a" and "b" are shown as 'Rectangle' objects in the Workspace, they actually come from two different classes, and therefore have different properties:

>> a = annotation('rectangle');
>> b = rectangle;
>> class(a)
ans =
    'matlab.graphics.shape.Rectangle'
>> class(b)
ans =
    'matlab.graphics.primitive.Rectangle'

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MATLAB: How to add a background rectangle to figure using figure toolbar

You cannot place a rectangle in the background using 'insert' -> 'rectangle'.

Instead, create the rectangle in the command window / script and just add shapes/lines as desired, adding the object you want on top last. For example:

>> figure1 = figure;
>> axes1 = axes('Parent', figure1);
>> hold(axes1,'on');
>> rectangle('Parent',axes1,'Position',[3 3 3 3],'FaceColor',[1 0 0]); % Plots the rectangle
>> plot(1:10); % Plots the line

'Insert' -> 'rectangle' actually creates an annotation in the shape of a rectangle, rather than just a rectangle.

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);

Best Answer

Related Solutions

MATLAB: How to add a background rectangle to figure using figure toolbar

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

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