Extracting coordinate values from a 3-D matrix

Question

Amy Eisenstadt 2017-12-16

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https://ww2.mathworks.cn/matlabcentral/answers/373305-extracting-coordinate-values-from-a-3-d-matrix

回答： Star Strider 2017-12-16

Screen Shot 2017-12-16 at 1.22.23 PM.png

I have a set of satellite data that is shown in the attachment. The latitude and longitude coordinates are given in two separate arrays of different sizes, latitude being a 1x72 array and longitude being a 1x192 array. They are attached to daily chlorophyll measurements in the variable chl_daily, which is a 72x192x366 matrix. The layers in this matrix are latitude, longitude, and day of the year. The values given in chl_daily, however, are concentration measurements of chlorophyll, and the latitude and longitude data that those points are connected to are not given in that matrix. I want to be able to plot chlorophyll concentrations spatially, on a map of the area, based on their associated coordinate location in latitude and longitude. My goal is to generate a matrix with three rows, where the first row is latitude, the second is longitude, and the third is the concentration derived from chl_daily for a particular day of the year. I have indexed into chl_daily for the day in question, which is chl_daily(:,:,222). Any help is greatly appreciated. Please let me know if you need access to the data itself, or more information. Thank you.

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Answer 1

Star Strider 2017-12-16

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https://ww2.mathworks.cn/matlabcentral/answers/373305-extracting-coordinate-values-from-a-3-d-matrix#answer_296568

在 MATLAB Online 中打开

I would do something like this:

lat = 1:7;                          % Create Test Data
lon = 1:9;                          % Create Test Data
chl_daily = rand(7, 9, 10);         % Create Test Data
[La,Ln] = meshgrid(lat, lon);
LatV = La(:);
LonV = Ln(:);
Chl_Mtx = reshape(chl_daily, numel(lat)*numel(lon), []);
LatSz = length(lat);
figure(1)
day = 2;
surf(reshape(LatV,[],LatSz), reshape(LonV,[],LatSz), reshape(Chl_Mtx(:,day), [], LatSz))
grid on

I don’t have the Mapping Toolbox. It may have utility functions that make this much easier. (I restricted the test data to make debugging and checking easier. My code should scale appropriately to your problem.)