Read .dat file in the format of a 3D matrix

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DM 2021-4-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/799442-read-dat-file-in-the-format-of-a-3d-matrix

编辑： Rupesh 2024-2-29

Hi,

I have a .dat file which is an output from IDL. This is a float 3D matrix with dimensions [145, 145, 249]. I tried to read it in Matlab as a 3D matrix unfortunately without success.

I tried the Import Tool app and many other solutions that I found online but none of them is working for my data:

https://uk.mathworks.com/matlabcentral/answers/89380-read-numbers-from-dat-file-in-the-format-of-a-3d-matrix

https://uk.mathworks.com/matlabcentral/answers/399296-how-to-load-a-dat-file

https://uk.mathworks.com/matlabcentral/answers/64787-how-to-load-dat-or-even-txt-files-into-matlab-workspace

I am using the following code to import a .dat file in IDL and it works fine.

%Define image dimensions and file name
Image = ‘Mydata.dat’
Nx = 145
Ny = 145
Nt = 249
%specify the .dat file path 
Path = ‘C:Users\’
%create an empty array 
Data = fltarr(Nx,Ny,Nt)
openr, 1, path + Image
readu, 1, data
close, 1

I would like to do something similar in Matlab. Any help would be greatly appreciated.

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KSSV 2021-4-12

How is your .dat file? What is it's format?

DM 2021-4-12

.dat file is basically a 3D image with floatting point values

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Answer 1

Rupesh 2024-2-16

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https://ww2.mathworks.cn/matlabcentral/answers/799442-read-dat-file-in-the-format-of-a-3d-matrix#answer_1410063

编辑：Rupesh 2024-2-29

在 MATLAB Online 中打开

Hi DM,

After looking over your sample code, which you have provided, I realised that your objective is to read the .”dat” file data into 3D matrix output with desired dimensions. I am aware that this process may be a little challenging if you don't have access to the “fltarr”,”openr”, and “readu” functions in Matlab. However, you can still accomplish a comparable outcome by running the following commands in MATLAB script.

open the binary “.dat” file for reading
read the floating-point data into MATLAB array.
Reshape the 1D array read from the file into a 3D matrix with correct dimensions.
Handle any potential issues such as file access errors or incorrect data interpretation due to endianness.

You can refer to below provided code snippet on how to read .Dat file and perform some operations on them.

%First portion of code  to create a sample .dat file for testing with given
%specification 
% Define image dimensions
Nx = 145;
Ny = 145;
Nt = 249;
% Generate random data
Data = rand(Nx, Ny, Nt, 'single');
% Specify the file path
Path = 'C:\checkoutput\'; % Make sure to use a path that is writable
Image = 'SampleMydata.dat';
FilePath = fullfile(Path, Image);
% Open the file for writing in binary mode
fileID = fopen(FilePath, 'wb');
% Check if the file was opened successfully
if fileID == -1
    error('File could not be opened, check the name or path.');
end
% Write the data to the file in single precision
fwrite(fileID, Data, 'single');
% Close the file
fclose(fileID);
% Display a message
disp(['Sample .dat file created at: ' FilePath]);

Here the second portion contributes to reading the .dat file data into desired dimensions.

%Second Portion of code where file is  created ,we can apply mathematical operations on the file 
% to read the floating point data present in it 
% Define image dimensions and file name
Nx = 145;
Ny = 145;
Nt = 249;
% Specify the .dat file path
Path = 'C:\checkoutput\'; % Make sure to use the correct path
Image = 'SampleMydata.dat';
FilePath = fullfile(Path, Image);
% Open the file for reading in binary mode
fileID = fopen(FilePath, 'rb');
% Check if the file was opened successfully
if fileID == -1
    error('File could not be opened, check the name or path.');
end
% Read the data assuming it is of type 'single' (4 bytes per number)
% fread reads the data into a 1D array, so we will need to reshape it later
Data = fread(fileID, Nx*Ny*Nt, 'single');
% Close the file
fclose(fileID);
% Reshape the data to the correct dimensions
% The order of dimensions may vary depending on how the data is written
% Here, we assume that the first dimension changes fastest, then the second,
% and the third dimension changes slowest
Data = reshape(Data, [Nx, Ny, Nt]);