Why does FILL give me dimension errors when my inputs are grouped, such as fill([x1, x2], [y1,y2],[c1,c2]) in MATLAB 7.7 (R2008b)?

I want to use FILL to color two rectangles – having their ‘x’ and ‘y’ coordinates grouped in ‘X’ and ‘Y’, and their colors as '[r g b]' grouped in C. I get an error when I execute:

x = [0 1 1 0; 1 4 4 1];   % x coordinates for two rectangles 

y = [0 0 2 2; 0 0 2 2];   % y coordinates for two rectangles 

c = [1 0 0; 0 0 1];       % red for one rectangle and blue for the other

fill(x,y,c)

 ??? Error using ==> fill

 Size of C must match sizes of X Y [Z]

Answer 1

[MathWorks Support Team]

Grouped inputs can be used for FILL in MATLAB 7.7 (R2008b).

To use FILL for multiple polygons with different colors, the syntax is:

>> fill(X1,Y1,C1,X2,Y2,C2,...),

in which ‘X1’ and ‘Y1’ define the coordinates of the first rectangle and ‘C1’ defines the color as ‘[r g b]’ or ‘colorstring’. If you group the X and Y coordinates as well as colors for two rectangles before calling FILL, they need to be comma-separated by converting matrices to CELL so that X1, Y1, C1, X2, Y2, and C2 can be called. The following MATLAB code provides an example:

% Assuming you have rectangles defined in "x", "y" and colors in "c"

x = [0 1 1 0; 1 4 4 1];

y = [0 0 2 2; 0 0 2 2];

c = [1 0 0; 0 0 1];

% Convert to cell array and rearrange appropriately

% To return output of cell arrays X, Y, and C, execute X{:}, Y{:}, and C{:}

X = num2cell(x, 2);

Y = num2cell(y, 2);

C = num2cell(c, 2);

args = [X Y C]';

args = args(:);

% "args{:}" expands to comma-separated list, hence you can call FILL directly

fill( args{:} )