Plot matlab color map with transparency on x axis

transparency_color_map.m

G = figure('color', [.5 .5 .5], 'Units', 'Normalized', 'Position', [0.5, 0.4, 0.06, 0.35]);

CM =  colormap;

% x represents the range in alpha (e.g abs(t-stats))
x = linspace(1, 1000, 256);
% y represents the range in hue (e.g power)
y = linspace(1, 1000, 1000);

[X,Y] = meshgrid(x,y); % Transform into a 2D matrix

axis xy;
box on
xlabel('t value')
ylabel('power')
set(gca, 'Xcolor', 'k', 'Ycolor', 'k')
set(gca, 'YAxisLocation', 'right')

% Plot the colorbar
imagesc(x,y,Y); 
colormap(flipud(CM));
alpha(X);
alpha('scaled');