using surf for 3D plot

Question

Ray 2015-10-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/247174-using-surf-for-3d-plot

回答： Walter Roberson 2015-10-7

Hello,

I am trying to plot a power against x and y positions for multiple files. The positions are the same for all the files however the power varies from one file to another. I have 3 separate mat files xpositions, positions, and power. when i load the files and try to plot i get this error "Undefined function or variable 'xpositions'.

The code is shown below:

myFolder = '/Users/redhwanmawari/Documents/MATLAB/2DimenstionalTestingGT20150907/MeasurementDataFinal/LOS0dbm15ft_finalData'; % Define your working folder
if ~isdir(myFolder)
  errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
  uiwait(warndlg(errorMessage));
  return;
end
filePattern = fullfile(myFolder, '*.mat');
matFiles = dir(filePattern);
 load('xpositions.mat');
 load('ypositions.mat');
for k = 1:length(matFiles)
%for k = 1:1
    baseFileName = matFiles(k).name;
    fullFileName = fullfile(myFolder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    matData{k} = load(fullFileName);
    figure
     [xpositions,ypositions] = meshgrid(xpositions,ypositions);
   surf(xpositions,ypositions,rawdata.matData(k));
   hold on

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Answer 1

Walter Roberson 2015-10-7

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https://ww2.mathworks.cn/matlabcentral/answers/247174-using-surf-for-3d-plot#answer_195011

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That suggests that your xpositions.mat does not have a variable named "xpositions".

Note:

[xpositions,ypositions] = meshgrid(xpositions,ypositions);

would overwrite xpositions and ypositions, which going to be a problem because you have it in a loop. Since your xpositions and ypositions do not change, meshgrid outside the loop and use the meshed variables inside the loop.