How do I create a polygon from coordinates?

I have a black image and with the program I have so far I'm plotting coordinates from a txt file on the image. What I wanna do is modify the image by creating lines between the coordinates and make it look like a polygon. How can I do that?

 [m, n] = size(dataTxt); 
    o_str = imshow(foto,'Parent', handles.axes1);
  for i = 1:n
        [p, q] = size(dataTxt{i});

        if (dataTxt{i}(p,1) == 1)
            color_display= 'ro';
        elseif (dataTxt{i}(p,1) == 2)
            color_display= 'bo';
        end
        for j = 1:p
            x = dataTxt{i}(j,1)
            y = dataTxt{i}(j,2)
            hold on; plot(x, y, color_display);

        end
        a  = num2str(i);
        text(dataTxt{i}(1,1), dataTxt{i}(1,2), a);
    end

Answer 1

[Walter Roberson]

        if (dataTxt{i}(p,1) == 1)
            color_display= 'ro-';
        elseif (dataTxt{i}(p,1) == 2)
            color_display= 'bo-';
        end
        x = dataTxt{i}(:,1)
        y = dataTxt{i}(:,2)
        plot(x, y, color_display);