MATLAB: Line through polygon using patch

edgealphaedgecolorpatchtransparencytransparent lines

I am trying to use a work-around in order to make a transparent line. It works, however, I keep getting a line through the middle of my graphic. Can somebody please tell me why?
    x = linspace(0,10);
    y1 = 4 + sin(x).*exp(0.1*x);
    y2 = 4 + cos(x).*exp(0.1*x);
    patch(x, y2, 'w', 'EdgeColor', 'r', 'EdgeAlpha', 1, 'FaceColor', 'r', 'FaceAlpha', 1)
    hold on
    patch(x, y1, 'w', 'Edgecolor', 'b', 'EdgeAlpha', 0.3, 'FaceColor', 'w', 'FaceAlpha', 0)
    hold off

Best Answer

Patch wants to draw closed polygons. If you don't want the line from the end of the second patch back to the beginning, then the easiest way is to add a nan like this:
x = linspace(0,10);
y1 = 4 + sin(x).*exp(0.1*x);
y2 = 4 + cos(x).*exp(0.1*x);
patch(x, y2, 'w', 'EdgeColor', 'r', 'EdgeAlpha', 1, 'FaceColor', 'r', 'FaceAlpha', 1)
hold on
patch([x nan], [y1 nan], 'w', 'Edgecolor', 'b', 'EdgeAlpha', 0.3, 'FaceColor', 'w', 'FaceAlpha', 0)
hold off
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