Plot data for a for specific x and y coordinates

Question

dylan price 2018-6-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/406108-plot-data-for-a-for-specific-x-and-y-coordinates

评论： Chandra Shekhar Lohani 2022-11-28

I have some data indicating precipitation at various coordinates in the world that I would like to plot. Each horizontal line is a combination of longitude (170...), lattitude (-72...) and precipitation (2...).

5   -72.5      2.11
5   -72.5      3.16
5   -72.5      2.69
5   -72.5      2.79
5   -72.5      2.41

I would like to plot the precipitation values for each set of xy coordinates as a chart with a colour scale varying for the precipitation amount. ie. x axis would be longitude, y axis lattitude and the chart would have multitude of different coloured points at their respective xy locations.

I have tried:

lat=dition;
lon=HDRAd;
data=al_ProcessingMap_Area_Averages_Removed;
lon=str2double(lon);
[lon,lat,data]=meshgrid(lon,lat,data);
surf(lon,lat,data)

which returns Error using repmat Maximum variable size allowed by the program is exceeded.

Error in meshgrid (line 77) xx = repmat(xx, ny, 1, nz);

Error in ecco (line 24) [lon,lat,data]=meshgrid(lon,lat,data);

The same thing with a truncated dateset yields this:

lat=dition;
lon=HDRAd;
data=al_ProcessingMap_Area_Averages_Removed;
lon=str2double(lon);
lon=lon(1:10)
lat=lat(1:10)
data=data(1:10)
[lon,lat,data]=meshgrid(lon,lat,data);
surf(lon,lat,data)

Error using matlab.graphics.chart.primitive.Surface/set Value must be a vector or 2D array of numeric type

Error in matlab.graphics.chart.internal.ctorHelper (line 6) set(obj, pvpairs{:});

Error in matlab.graphics.chart.primitive.Surface

Error in surf (line 150) hh = matlab.graphics.chart.primitive.Surface(allargs{:});

Error in ecco (line 12) surf(lon,lat,data)

I have also tried

map=pcolor(lon,lat,data)

to no avail. It feels like such a simple problem that I'm struggling with! Any help is much appreciated

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Rik 2018-6-18

It looks like you need to reshape the data, not use meshgrid. You already have all (x,y,z) pairs, so you only need to put it in a shape that surf likes. If you attach a .mat with your data we can help you with reshape. You can also show some code that will generate similarly shaped data.

dylan price 2018-6-18

ecco.mat

Thanks for the tip, I'll have a look at reshape. I've attached a .mat file

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Answer 1

Rik 2018-6-18

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/406108-plot-data-for-a-for-specific-x-and-y-coordinates#answer_325101

在 MATLAB Online 中打开

ecco.mat

You have holes in your data (i.e. not all grid positions have data). Therefore surf will not work. You can either choose to plot the data itself, or interpolate it. The code below shows how to do either.

lat=dition;
lon=str2double(HDRAd);
data=al_ProcessingMap_Area_Averages_Removed;
[lat_q,lon_q]=meshgrid(unique(lat),unique(lon));
F = scatteredInterpolant(lat,lon,data);
interpolated_data=F(lat_q,lon_q);
figure(1),clf(1)
%if you want to show the actual data itself as a scatterplot:
%plot3(lat,lon,data,'.'),hold on
surf(lat_q,lon_q,interpolated_data)