Fill between two lines not working

I am trying to fill the between the lines but its is only plotting the limiting lines. I cant seem to understand the problem.

Hope you can help. Thanks in advance.

figure(2)

    semilogx((f_Along)*(0.1/WS),f_Along.*((PSD_AL_M))/WSP^2,'Color',...
        'k','LineWidth',2)
    hold on
    semilogx((f_Along)*(0.1/WS),f_Along.*((SD_AL_P))/WSP^2,'Color',...
        [0.7 0.7 0.7],'LineWidth',2,'DisplayName','STD+')
    hold on
    semilogx((f_Along)*(0.1/WS),f_Along.*((SD_AL_N))/WSP^2,'Color',...
        [0.7 0.7 0.7],'LineWidth',2,'DisplayName','STD-')
    hold on
    x2 = [(f_Along')*(0.1/WS), fliplr((f_Along')*(0.1/WS))];
    inBetween = [f_Along'.*((SD_AL_P'))/WSP^2, fliplr(f_Along'.*((SD_AL_N'))/WSP^2)]
    fill(x2, inBetween,  'k');
    hold on

[Walter Roberson]

We will probably need your variables to test with.

[Walter Roberson]

It would be easier if we had your data so we could test on our own system to avoid accidentally giving you a solution that does not work for your situation.

[Saugat Shrestha]

I have attached the variables.

Thanks in advance.

Answer 1

[Star Strider]

Plot everything (including the patch calls) using linear axis rulers first, then convert the scale to logarithmic.

See How can I shade confidence intervals on a loglog plot? for an example.

.

[Saugat Shrestha]

Plotting in the linear scale, it works fine but still is not shaded when I change into lag log graph.

[Star Strider]

It is necessary to plot in the linear scale, including the patch calls, then do:

set(gca, 'XScale','log')

Example —

x = logspace(-2, 1, 250);
y = sin(2*pi*x);
hi = y + 0.2;
lo = y - 0.2;

figure
plot(x, y)
hold on
patch([x, fliplr(x)], [hi fliplr(lo)], 'r', 'FaceAlpha',0.25)
hold off
grid
set(gca, 'XScale','log')

Run this example, then apply it to your code.

[Saugat Shrestha]

I still get the same problem. It appears in the linear scale. But doesnt appear in the log scale.

[Walter Roberson]

what is min() of the y coordinates of the data you are trying to fill between?

[Saugat Shrestha]

The min() of the y coordinates of the data I am trying to fill between is zero (0).

[Walter Roberson]

fill() creates a 2D patch with a continuous edge.

In MATLAB, when you use patch() on a log scale, then any face that has a coordinate of 0, or a negative number, or nan, in it is not drawn. The edges that are entirely within the limits would still be drawn, though. This leads to situations where the edge of a fill area is drawn but the area is not filled.

This is happening to you because your first and last x2 coordinates are 0. Based on your sample graphs you probably want to use max(1e-4,x2) as the x coordinates.

[Star Strider]

@Saugat Shrestha — It would have helped to have had your data at the outset. As Walter points out, the problem is that ‘f_Along’ begins with 0. Since log(0) appraches -Inf, the transformation fails for patch.

Add before you create ‘figure(2)’:

f_Along = f_Along + eps;

and after the patch (or fill) call:

xlim([f_Along(2) f_Along(end)])
set(gca, 'XScale','log')

@Walter — Thank you.

.

[Saugat Shrestha]

@Walter Roberson, I did as you instructed and it worked.

Thank You so much.