Plots are stuck on semi-log axis

I have created an app that plots on UIAxes either with a plot command or semilogx command depending on a switch value. But once I have plotted with semilogx I am unable to revert to a linear x axis with subsequent executions of the code. The code snippet is shown below. The pasted image shows a bode response with points displayed with the red "x" called out in the regular plot command as opposed to the red "o" used in the semilogx command. I had set a breakpoint in the code and it clearly stopped in the 'Linear' case for every one of these plots. Why doesn't plot result in a linear x-axis?

                % Plot results
                switch app.FrequencyAxisSwitch.Value
                    case 'Linear'
                        plot(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'rx');
                        plot(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'rx');
                    case 'Logarithmic'
                        semilogx(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'ro');
                        semilogx(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'ro');
                end

Answer 1

[Image Analyst]

I'm not sure you're going into the case you think you are, especially since the code for ylabel is not there so I can't tell which case you did. How/where are you setting the ylabel?

If you put a break point there at the switch, are you sure you're stepping into the linear one and doing the regular plot() call? What happens if you do this before the switch?

cla reset

[Pat Gipper]

Hi & thanks. The label was set in the code when the axes are created in the figure window. The axis labels are never changed after that point so I never have to re-label the axes.

I did have a break point at the switch and saw that the axes are re-plotted, but as semilogx, despite it being the Linear case. I'll try your suggestion for the cla reset next.

The snippet of code that creates the axes is shown below.

            % Create UIAxes2
            app.UIAxes2 = uiaxes(app.FrequencyResponseAnalyzerUIFigure);
            title(app.UIAxes2, '')
            xlabel(app.UIAxes2, 'Frequency - [Hz]')
            ylabel(app.UIAxes2, 'Y')
            app.UIAxes2.Visible = 'off';
            app.UIAxes2.Position = [467 370 480 304];

            % Create UIAxes3
            app.UIAxes3 = uiaxes(app.FrequencyResponseAnalyzerUIFigure);
            title(app.UIAxes3, '')
            xlabel(app.UIAxes3, 'Frequency - [Hz]')
            ylabel(app.UIAxes3, 'Y')
            app.UIAxes3.Visible = 'off';
            app.UIAxes3.Position = [467 27 480 299];

[Image Analyst]

If the string is Linear and goes into the Log case, you might try casting everything to lower,

                % Plot results
                switch lower(app.FrequencyAxisSwitch.Value)
                    case 'linear'
                        plot(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'rx');
                        plot(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'rx');
                    case 'logarithmic'
                        semilogx(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'ro');
                        semilogx(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'ro');
                end

or else use contains()

                % Plot results
                if contains(app.FrequencyAxisSwitch.Value, 'Linear', 'IgnoreCase', true)
                        plot(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'rx');
                        plot(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'rx');
                else
                        semilogx(app.UIAxes2,fra_fvec(1:i_fra),mg21(1:i_fra),'ro');
                        semilogx(app.UIAxes3,fra_fvec(1:i_fra),ph21(1:i_fra),'ro');
                end
                

If before those you put

whos app.FrequencyAxisSwitch.Value

what does it show in the command window? I want to make sure it's a character array, and not a number or something.

[Pat Gipper]

Bingo! We have a winner. Your original suggestion to use cla worked, but it is a little more complicated with handles. The plot and semilogx commands were in a loop in a section of code that is entered as a result of a callback from a pushbutton. I just needed to clear the axes prior to the loop. I did need to re-apply the label to the axes. Here is the code snippet with your suggestion.

            cla(app.UIAxes2,'reset');% Answer 711488 "Image Analyst" suggestion
            grid(app.UIAxes2,'on');
            xlabel(app.UIAxes2, 'Frequency - [Hz]')
            app.UIAxes2.Visible='on';
            cla(app.UIAxes3,'reset');% Answer 711488 "Image Analyst" suggestion
            grid(app.UIAxes3,'on');
            xlabel(app.UIAxes3, 'Frequency - [Hz]')
            app.UIAxes3.Visible='on';
             switch app.OutputStyleSwitch.Value
                 case 'Real/Imaginary'
                     ylabel(app.UIAxes2,'Real')
                     ylabel(app.UIAxes3,'Imaginary')
                 case 'Magn(dB)/Phase(Deg)'
                     ylabel(app.UIAxes2,'Magnitude - [dB]')
                     ylabel(app.UIAxes3,'Phase - [Deg]')
             end