Undefined function 'drawrectangle' for input arguments of type 'char'?

Trying to utilize the 'drawrectangle' function but it's giving me the error you see in the question. I am using R2018a.

This for loop I created (seen below) is to place a series of rectangles of a pre-defined length onto an image. The RawRNA.Data structure are all numbers and correctly defined with the columns of x1, y1, x2, and y2, respectively.

Both variables "w" and "h" (the respective lengths of the rectangle) are being correctly defined too. Below is a screenshot of what RawRNA.Data looks like.

Am I missing something fundamental in the code? Assume everything else before 'drawrectangle' is correctly defined. I'm also happy to provide additional information as you need.

numberofrectangles1=size(RawRNA.Data,1);
A=false(dims.vRNA.(NHPname)(1),dims.vRNA.(NHPname)(2));
figure('Position',[1 1 dims.vRNA.(NHPname)(2) dims.vRNA.(NHPname)(1)])
imshow(adj.vRNA.(NHPname))
axis image;
hold on;
for k = 1 : numberofrectangles1
    w=(RawRNA.Data(k,3)-RawRNA.Data(k,1));
    h=(RawRNA.Data(k,4)-RawRNA.Data(k,2));
    rect=drawrectangle('Position',[RawRNA.Data(k,1),RawRNA.Data(k,2),w,h],'Color','r','LineWidth',1);
    rna_roi=createMask(rect);
    for j = 1 : dims.vRNA.(NHPname)(1)
        for n = 1 : dims.vRNA.(NHPname)(2)
            if rna_roi(j,n)==1
                A(j,n)=1; 
            end  
        end
    end
end

Answer 1

[Image Analyst]

drawrectangle() was not introduced until R2020a. You will have to use rbbox() or imrect() instead.