Help changing axis direction with for loop plot.

Hello,

I am trying to graph data from excel with a for loop but I need to reverse and log my x axis. I figured out how to log the axis but trying to use set(gca,''XDir','reverse') does not work. It gives the error "Unable to use a value of type matlab.graphics.axis.Axes as an index.". Thanks for any advice. Here is also an example of what I'm looking to achieve as far as the axis is concerned.

data = xlsread('Field_Testing','GrainSize');
sz = size(data);
rows = sz(1);
colms = sz(2);

set1 = data(:,[1,2]);


c = {};

for j = 1:colms
    if rem(j,2) == 0
        set = data(:, [j-1, j]);
        c{end+1} = set; %saves to end of each previous cell
    end
end

figure()

for z = 1:(colms/2)
    arr = c{z};
    arr = rmmissing(arr);
    x = arr(:,1);
    y = arr(:,2);
    
    p = semilogx(x,y);
    set(gca,'XDir','reverse')
    
    hold on
end
hold off

[Les Beckham]

I'm not real sure how you would go about creating a 'reverse' log axis. Perhaps you could plot 1/x and then manually set the axis tick labels.

I do know for certain that you should never ever name a variable 'set' (like you did here: set = data(:, [j-1, j]);). This is probably the most common function name in Matlab. Overriding it with a variable will almost certainly break a lot of things, including the graphics routines that you need to make any kind of plot.

[Cody Arnold]

Oh ok, thanks for the tip I really appreciate it!

By reverse I mean I want the axis to plot in descending order. It should be in log scale as well but I already got that part with semilogx. Removing the vairable set seems to have fixed it! thanks again!

[Les Beckham]

I'm glad that helped. As far as doing the 'reverse' log, you might try my idea of plotting 1/x instead of x and experiment to see if that gets you closer to what you want.