Grid 2D matrix to xyz

I have file trend.mat as a Grid 2D martix and i am trying to use the following code to convert it to xyz in csv file. where the size (trend)= 180 * 360 which mean each value in trend have xy values but this code has a problem in dimension.

load('trend.mat');
[lon,lat] = size(trend);   %  matrix dimension must be (y) to latitude,  (X) to longitude
tws = trend    %(:);          % tws is the trend values of water hieght Variation
lon=linspace(0,1,360);      %lon=0:360;  
lat=linspace(90,-1,-90);      %lat=90:-1:-90;
file = fopen('Trend.csv','w');
for y = 1:180
for x = 1:360
fprintf(file, strcat(num2str(lat(y)),',',num2str(lon(x)),','));
for z=1:1
fprintf(file, '%.16g,',tws(x,y,z));      
end;
    fprintf(file,'\n');
end;
end;
fclose(file);

Answer 1

[John BG]

Karem

you have crossed x and y in the fprinf writing to file. Your code corrected:

load trend.mat
[lon,lat] = size(trend);           % Where X = 360   &  Y = 180 the dimension of matrix
      lon=0.5:359.5;      
      lat=89.5:-1:-89.5;
tws = trend;
file = fopen('Trend.csv','w');
for y = 1 : 180
  for x = 1: 360
        fprintf(file,strcat(num2str(lat(y)),',',num2str(lon(x)),','));
    fprintf(file, '%.16g,',tws(y,x));      
    fprintf(file,'\n');
  end;
end;
fclose(file);

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thanks in advance

John

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[karem Fathy]

Hi John It's working, Thanks so much for your help. I appreciate your efforts.

Answer 2

[Walter Roberson]

lat=linspace(90,-1,-90);

would mean that you wanted to have negative 90 points in the range 90 to -1 . You cannot create negative 90 points.

linspace(A,B,N) is for creating N points that run from A to B

You probably want the colon operator, 90 : -1 : -90 and 0 : 1 : 360

[Image Analyst]

Funny that the line was right in the first place and then they commented out the correct code and inserted incorrect code. If they really wanted linspace instead of colon they should have done

lon=linspace(0, 360, 361)
lat=linspace(90, -90, 181)

But for integer steps, the color operator, like they used initially, is the simplest way to go.

And to be robust, these lines need to be changed to this:

for y = 1 : length(lat)
for x = 1 : length(lon)

[karem Fathy]

Hello, I edited the code to the following format but I still have a problem with printing the data to a csv file.

Convert the mat file of "Trend" Grid 2D matrix to xyz in CSV file

load ('trend.mat')

[lon,lat] = size(trend);           % Where X = 360   &  Y = 180 the dimension of matrix

      lon=0.5:359.5;      
      lat=89.5:-1:-89.5;

tws = trend;

file = fopen('Trend.csv','w');

for y = 1 : 180

  for x = 1: 360
    
    

fprintf(file,strcat(num2str(lat(y)),',',num2str(lon(x)),','));
    
      fprintf(file, '%.16g,',tws(x,y));      

    fprintf(file,'\n');
  end;
end;
fclose(file);

[Image Analyst]

Attach trend.mat so we can try things. Also, explain what "I still have a problem" means exactly.

To format your code so that it looks normal, see this:

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[karem Fathy]

Please find the attached file. I mean with ruining the code, i got an error massage "Index exceeds matrix dimensions".