Set non-uniform axis - extension of certain part of y-axis.

I want to extend a certain section of the y-axis in a contour plot. For e.g., 0 to 200 m and 200 to 400 m depths are extended to different extents in a plot as shown in the attached figure.

Is there a direct function to do so?

If not the extension of multiple sections of axis, 'function' for extension of one section only shall also work.

[Adam Danz]

How was the plot generated?

Is the yscale linear?

Were the y-ticks manually set?

[Himanshu Saxena]

The plot was generated using ODV (Ocean Data View) software.

Yes, the y scale is linear.

No, there is a direct command in ODV to exted the top y-axis. Thus, ODV itself sets the y-ticks and labels.

[Adam Danz]

That doesn't make sense to me.

The y-axis ticks are clearly not linearly spaced which only happens when the y-axis is log-scale or if the ticks were manually placed.

I'll add an answer that approximates your description.

[Himanshu Saxena]

Kindly note that this plot was made by me in ODV software and the ticks were not manually placed. Also, the y-axis is not in log scale.

The y-axis is simply stretched more at some range and shrinked at the other.

I appreciate your solution to my question but unfortunately I'm not looking for a solution that includes the conversion of y-scale to log scale.

[Adam Danz]

> The y-axis is simply stretched more at some range and shrinked at the other.

If that's the case, then the y-axis is not linearly spaced.

In Matlab the axes can be linear or log spaced. There is no other non-linear spacing option which is probably a good thing because if the tick intervals are non-linear and not log-scale, it's difficult, no, impossible to interpret any part of the data that is not parallel to a labeled tick unless the sections of the axes between ticks are linear but that still makes it difficult to interpret that plot.

If you provide a link to the documentation in ODV that explains the axis-scaling you used, I might better understand what it's doing.

[Himanshu Saxena]

I do not see the documentation online regarding that explanation. But I have attached a screenshot of the software that clearly shows that the y-axis can be stretched without converting it into log scale.

So now I know MATLAB do not stretch the axes, I cannot plot such plot.

[Adam Danz]

The ODV User Guide unfortunately doesn't mention how they implement the appearance of a strechted y-axis. The tick-intervals are not linear nor do they appear to be logarithmic which are the only two options in Matlab.

To create plots that appear to have nonlinear axes that aren't logrithmic, you can stretch the data itself and apply axis ticks and tick-labels accordingly.

Note that applying a log-axis does stretch the upper portion of the data as shown in my answer, but differently than what appears in the ODV plots you shared.

Answer 1

[Adam Danz]

The y-axis in your image is log-scaled and flipped. However, log(0) is undefined (it's -inf in matlab) so the 0-tick in the image makes me believe that the tick labels were manually placed.

Here's an example, of a log-scale on the flipped y-axis with custom ticks but without changing ticklabels.

ax = axes(); 
[X,Y,Z] = peaks;
contourf(X,(Y+3)*233.33,abs(Z),7)

ax.YDir = 'Reverse'; 
ax.YScale = 'log';
ax.YTick =[100 200 400 600 800 1000 1400];
ax.TickDir = 'out';
ylim([100 1400])
colormap(flipud(turbo(255)))