contours plot over heat map in matlab

Question

Muhammad Usman Saleem 2016-6-8

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编辑： Muhammad Usman Saleem 2016-6-20

I have temperature and elevation data set in text files.By using this code I am trying to plot contours of height over heat map( color map) but when I plot these contours, figure turned to blue and color bar of heat map changed.

My requirements

I want to plot heat map(color map) from temperature data and want to plot over it height contours.

Both text files and shapefile has been attached with this post.

I shall be very thankful for this assistance

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Answer 1

Kelly Kearney 2016-6-8

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By default, the color limits of an axis are set to span the maximum range of plotted objects that could use a colormap. In your case, contour plots can use the colormap to color lines, and even though you changed this behavior by setting the contour line color to blue, the colormap is still adjusting itself to the limits of that data.

You can fix it by simply changing the axis color limits:

set(gca, 'clim', [min(Ci(:)) max(Ci(:))]);

Now, if you actually want to display a separate colormap for the contour lines than for the underlying geoshow plot, then you'll have to use something like freezeColors (older Matlab) or to layer axes on top of each other with different colormaps (R2014b+). But that isn't necessary in your example.

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Kelly Kearney 2016-6-9

在 MATLAB Online 中打开

(Please be patient with time zones... you can't expect a reply from me at midnight)

1) I suppose that would depend on the format of your relative humidity data. If it's scattered data, you might be able to add a few points on top. But you would have to get creative with colormaps.

2) What version of Matlab are you running? The feezeColors function ( dowload here) was written back when Matlab only allowed a single colormap per figure. In newer releases (R2014b+), that's no longer the case. So if you're running a newer version of Matlab, I recommend layering axes rather than messing with freezeColors. Here's a quick example:

% 3 datasets, with different ranges
[x,y,z] = peaks(50); % -6.53 <= z <= 8.05
z2 = rand(50);       % 0 <= z2 <= 1
z3 = (x + y) + 100;  % 94 <= z3 <= 106
% Create two axes on top of each other  
ax(1) = axes;
ax(2) = axes('position', ax(1).Position);
% Plot datasets 1 and 2 on the first axis
% (#2 doesn't need a colormap, so it can share)
pcolor(ax(1), x, y, z2);
shading(ax(1), 'flat');
hold(ax(1), 'on');
contour(ax(1), x, y, z, 'b');
set(ax(1), 'clim', [0 1]);
% Plot #3 on the second axis, as scattered colored dots
scatter(ax(2), x(:), y(:), 10, z3(:), 'filled');
set(ax(2), 'Color', 'none', 'xtick', [], 'ytick', []);
% Give each axis a different colormap and colorbar
colormap(ax(1), gray);
colormap(ax(2), parula);
cb(1) = colorbar('peer', ax(1), 'location', 'east');
cb(2) = colorbar('peer', ax(2), 'location', 'west');

Of course, layered axes like this can get be difficult to read, as in this example. I like it in certain instances; for example, layering a geolocated pcolor plot on top of shaded topography/bathymetry. Whether this layering will work for you depends on how cohesive your datasets are. Separate subplots may be a better option.

Kelly Kearney 2016-6-16

1 & 2. This is a research question, not a Matlab one. Yes, you can visualize upper atmosphere data using Matlab. Exactly how you go about visualizing it is up to you... only you know what point you're trying to convey with those visualizations.

3. You want a pre-existing model for weather/climate forecasting, based on a single timeseries? Again, this is a research question. I'm sure there are plenty of small models out there written in Matlab (the true workhorse climate models are typically in Fortran)... if you get lucky, you may stumble upon one that has already built the exact model you need to address your question, and in Matlab to boot. But you'll probably need to build your own.

Muhammad Usman Saleem 2016-6-17

Let's discuss this topic in detail on Linkedin. I am here on LinkedIn . I think , I can discuss with you in detail research problem on meteorology, climatology there.

Now matlab,

Let say, I have three such kind of maps, which i want to show as sclice in 3d in matlab. Can you guide me how can i show this?

Thanks

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Answer 2

KSSV 2016-6-8

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Try using freezeColors after hold on..... You may get the funciton from the link: http://in.mathworks.com/matlabcentral/fileexchange/7943-freezecolors---unfreezecolors

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Muhammad Usman Saleem 2016-6-8

no ,this function only doing sub ploting in a figure. While i want to make contour plot on color map. Both temperature map and contour plot are of same regions and extend?

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