Help to plot a graph using the data file

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Ruthra 2025-12-5

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https://ww2.mathworks.cn/matlabcentral/answers/2181668-help-to-plot-a-graph-using-the-data-file

评论： Star Strider 2026-1-10，17:14

I have the data filefor the velocity, for which i need aplot a graph.

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Answer 1

Star Strider 2025-12-5

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2181668-help-to-plot-a-graph-using-the-data-file#answer_1572477

在 MATLAB Online 中打开

Perhaps something like this --

writematrix([0:10; sin(2*pi*(0:10)/20)].','Your_Data.csv') % Create File

Data = readmatrix('Your_Data.csv') % Read File

Data = 11×2

0 0 1.0000 0.3090 2.0000 0.5878 3.0000 0.8090 4.0000 0.9511 5.0000 1.0000 6.0000 0.9511 7.0000 0.8090 8.0000 0.5878 9.0000 0.3090 10.0000 0.0000

<mw-icon class=""></mw-icon>

Time = Data(:,1);

Velocity = Data(:,2);

figure

plot(Time, Velocity)

grid

axis('padded')

xlabel('Time')

ylabel('Veolcity')

title('Data')

●

.

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Star Strider 2025-12-5

在 MATLAB Online 中打开

I finally came up with a way to separate the files. It is not as straightforward as simply loading them and plotting them if they were originally given different names, however it distinguishes them and then plots them.

These appear similar to what you want, however I am not certain exactly what that is. (The resulting matrices are size (51x51) so I randomly chose the approximate centre of each (row/column 26) and plotted them. Yopu can set 'row_col' to be a vector (for exaample row_col = [1 26 51]) to plot multiple values from each matrix.

I have no idea what the 'AR' values are or how they relate to these matrices, so I just referred to the individual curves by the file names (that I assigned to them).

Try something like this --

filesc = {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844326/uvelo-vor.txt'; 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844327/vvelo-vor.txt'; 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844328/uvelo-vor.txt'; 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844329/vvelo-vor.txt'; 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844330/uvelo-vor.txt'; 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844331/vvelo-vor.txt'}

filesc = 6×1 cell array

{'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844326/uvelo-vor.txt'} {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844327/vvelo-vor.txt'} {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844328/uvelo-vor.txt'} {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844329/vvelo-vor.txt'} {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844330/uvelo-vor.txt'} {'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1844331/vvelo-vor.txt'}

for k = 1:floor(numel(filesc)/2)

ki = 2*k-1;

filenameu{k,:} = sprintf('uvelo-vor%d.txt',k);

ufile = websave('uvelo-vor', filesc{ki});

u{k} = readmatrix(ufile);

Uu = unique(u{k}(:,1));

ux{k} = reshape(u{k}(:,1), numel(Uu), []);

uy{k} = reshape(u{k}(:,2), numel(Uu), []);

uz{k} = reshape(u{k}(:,3), numel(Uu), []);

% u{k}

end

for k = 1:floor(numel(filesc)/2)

ki = 2*k;

filenamev{k,:} = sprintf('vvelo-vor%d.txt',k);

vfile = websave('vvelo-vor', filesc{ki});

v{k} = readmatrix(vfile);

Uv = unique(u{k}(:,1));

vx{k} = reshape(v{k}(:,1), numel(Uv), []);

vy{k} = reshape(v{k}(:,2), numel(Uv), []);

vz{k} = reshape(v{k}(:,3), numel(Uv), []);

% v{k}

end

row_col = 26

figure

hold on

for k = 1:3

plot(uz{k}(:,row_col), uy{k}(:,row_col), DisplayName=filenameu{k})

end

hold off

grid

xlabel('U')

ylabel('Y')

title('''U'' Matrices')

legend(Location='best')

●

figure

hold on

for k = 1:3

plot(vx{k}(row_col,:), vz{k}(:,row_col), DisplayName=filenamev{k})

end

hold off

grid

xlabel('X')

ylabel('V')

title('''V'' Matrices')

legend(Location='best')

.

Star Strider 2025-12-6

编辑：Star Strider 2025-12-6

@Ruthra --

My pleasure!

What I posted is the complete code. To copy all of it to your Clipboard, right-click on the 'Copy' icon in the upper right of the code section HERE

then paste that to an open tab in your MATLAB Editor.

For reference, the complete part of that line of code (the first line in my code) is this --

I had to figure out a way to separate the identically-named files into different files, and managed to do that. You will most klikely need to create a cell arrray of the complete paths to each of your files to your version of my 'filesc' cell array. Since the files themselves have identical names, they most likely exist in separate paths or at least directories, and my code needs to know where to find them.

Each file is actually 3 column vectors that the reshape function converts to (51x51) matrices of the 'x', 'y', and 'z' coordinates. I created those as individual cell arrays, since that makes indexing them easier. (I could have plotted those using the surf or similar functions. I decided not to since that was not requested.)

I suggest that you give unique names to your files., for example by appending numbers to them That will make this task much easier.

I have no idea what you actually want to plot, so I chose row or column 26 and plotted those from each file. You will need to experiment to see what rows or columns to plot.

I have no idea what the AR variable refers to. That information was not provided in connection with the files posted.

If my answer solves your problem, please Accept it!

.

EDIT -- Corrected minor formatting issue. Content unchanged.

.

Star Strider 2025-12-23，12:25

在 MATLAB Online 中打开

You will need to copy the paths to each file to the 'filesc' cell array, and then use those in the readmatrix calls in your code.

That would go something like this --

filesc = {'/YourBaseFilePath/YourInstrumentPath_1/uvelo-vor.txt'; '/YourBaseFilePath/YourInstrumentPath_1/vvelo-vor.txt'; '/YourBaseFilePath/YourInstrumentPath_2/uvelo-vor.txt'; '/YourBaseFilePath/YourInstrumentPath_2/vvelo-vor.txt'; '/YourBaseFilePath/YourInstrumentPath_3/uvelo-vor.txt'; '/YourBaseFilePath/YourInstrumentPath_3/vvelo-vor.txt'};
for k = 1:floor(numel(filesc)/2)
    ki = 2*k-1;
    filenameu{k,:} = sprintf('uvelo-vor%d.txt',k);
    u{k} = readmatrix(filesc{ki});
    Uu = unique(u{k}(:,1));
    ux{k} = reshape(u{k}(:,1), numel(Uu), []);
    uy{k} = reshape(u{k}(:,2), numel(Uu), []);
    uz{k} = reshape(u{k}(:,3), numel(Uu), []);
    % u{k}
end
for k = 1:floor(numel(filesc)/2)
    ki = 2*k;
    filenamev{k,:} = sprintf('vvelo-vor%d.txt',k);
    v{k} = readmatrix(filesc{ki});
    Uv = unique(u{k}(:,1));
    vx{k} = reshape(v{k}(:,1), numel(Uv), []);
    vy{k} = reshape(v{k}(:,2), numel(Uv), []);
    vz{k} = reshape(v{k}(:,3), numel(Uv), []);
    % v{k}
end
row_col = 26
figure
hold on
for k = 1:3
    plot(uz{k}(:,row_col), uy{k}(:,row_col), DisplayName=filenameu{k})
end
hold off
grid
xlabel('U')
ylabel('Y')
title('''U'' Matrices')
legend(Location='best')
figure
hold on
for k = 1:3
    plot(vx{k}(row_col,:), vz{k}(:,row_col), DisplayName=filenamev{k})
end
hold off
grid
xlabel('X')
ylabel('V')
title('''V'' Matrices')
legend(Location='best')

I do not know what operating system you are using, or how your file paths are structured, so I use

'/YourBaseFilePath/YourInstrumentPath_1/'

and so fortth, for that here.

I strongly suspect that your instrument is creating something similar to 'YourInstrumentPath_1' (with slightly different names that I use numbers for here) for each 'uvelo-vor.txt' and 'vvelo-vor.txt' file pair it creates. You need to provide those details, since I have no idea what they are on your computer, or how any of that is organised.

I have changed the rest of my code to use those file paths directly to read and plot your files. You will need to choose the correct values for 'row_col' (there may be more than one, in that event you can create a vector for them) and the code should work as written here without any other midifications.

.

Ruthra 2026-1-5，9:06

the above is the modified code, but still im not getting the graph

filesc = {'D:/matlab programs/uvelo1-vor.txt'; 'D:/matlab programs/vvelo1-vor.txt'; 'D:/matlab programs/uvelo2-vor.txt'; 'D:/matlab programs/vvelo2-vor.txt'; 'D:/matlab programs/uvelo3-vor.txt'; 'D:/matlab programs/vvelo3-vor.txt'};

for k = 1:floor(numel(filesc)/2)

ki = 2*k-1;

filenameu{k,:} = sprintf('uvelo-vor%d.txt',k);

u{k} = readmatrix(filesc{ki});

Uu = unique(u{k}(:,1));

ux{k} = reshape(u{k}(:,1), numel(Uu), []);

uy{k} = reshape(u{k}(:,2), numel(Uu), []);

uz{k} = reshape(u{k}(:,3), numel(Uu), []);

% u{k}

end

for k = 1:floor(numel(filesc)/2)

ki = 2*k;

filenamev{k,:} = sprintf('vvelo-vor%d.txt',k);

v{k} = readmatrix(filesc{ki});

Uv = unique(u{k}(:,1));

vx{k} = reshape(v{k}(:,1), numel(Uv), []);

vy{k} = reshape(v{k}(:,2), numel(Uv), []);

vz{k} = reshape(v{k}(:,3), numel(Uv), []);

% v{k}

end

row_col = 26

figure

hold on

for k = 1:3

plot(uz{k}(:,row_col), uy{k}(:,row_col), DisplayName=filenameu{k})

end

hold off

grid

xlabel('U')

ylabel('Y')

title('''U'' Matrices')

legend(Location='best')

figure

hold on

for k = 1:3

plot(vx{k}(row_col,:), vz{k}(:,row_col), DisplayName=filenamev{k})

end

hold off

grid

xlabel('X')

ylabel('V')

title('''V'' Matrices')

legend(Location='best')

Star Strider 2026-1-7，13:09

在 MATLAB Online 中打开

I tested it as far as I could, and it appears to assign the file names correctly. I re-tested my code as well, and it seems to work correctly.

Does your version of my code throw any errors or warnings?

Does it read the data? Check to see if there is anything in 'u{k}' and 'v{k}'.

I cannot determine if this is significant, however I note that is says that it opens with 'Notepad'. I no longer have access to Windows (I currently run Ubuntu on both my desktop and laptop), however it might be worthwhile changing that to open with 'MATLAB' or 'MATLAB Editor'.

Since I do not have access to your computer, you probably need to have someone in your research group help you determine what the problem is. My code works, however you need to get it to read your files. I cannot help you with that, beyond what I have already written. (The forward slants (/) should work in Windows, although Windows conventionally uses the back slant (\) as a separator. I doubt that is the problem.)

filesc = {'D:/matlab programs/uvelo1-vor.txt'; 'D:/matlab programs/vvelo1-vor.txt'; 'D:/matlab programs/uvelo2-vor.txt'; 'D:/matlab programs/vvelo2-vor.txt'; 'D:/matlab programs/uvelo3-vor.txt'; 'D:/matlab programs/vvelo3-vor.txt'};
for k = 1:floor(numel(filesc)/2)
    ki = 2*k-1;
    filenameu{k,:} = sprintf('uvelo-vor%d.txt',k)
    % u{k} = readmatrix(filesc{ki});
    % Uu = unique(u{k}(:,1));
    % ux{k} = reshape(u{k}(:,1), numel(Uu), []);
    % uy{k} = reshape(u{k}(:,2), numel(Uu), []);
    % uz{k} = reshape(u{k}(:,3), numel(Uu), []);
    % % u{k}
end
filenameu = 1×1 cell array
    {'uvelo-vor1.txt'}
filenameu = 2×1 cell array
    {'uvelo-vor1.txt'}
    {'uvelo-vor2.txt'}
filenameu = 3×1 cell array
    {'uvelo-vor1.txt'}
    {'uvelo-vor2.txt'}
    {'uvelo-vor3.txt'}
for k = 1:floor(numel(filesc)/2)
    ki = 2*k;
    filenamev{k,:} = sprintf('vvelo-vor%d.txt',k)
    % v{k} = readmatrix(filesc{ki});
    % Uv = unique(u{k}(:,1));
    % vx{k} = reshape(v{k}(:,1), numel(Uv), []);
    % vy{k} = reshape(v{k}(:,2), numel(Uv), []);
    % vz{k} = reshape(v{k}(:,3), numel(Uv), []);
    % v{k}
end
filenamev = 1×1 cell array
    {'vvelo-vor1.txt'}
filenamev = 2×1 cell array
    {'vvelo-vor1.txt'}
    {'vvelo-vor2.txt'}
filenamev = 3×1 cell array
    {'vvelo-vor1.txt'}
    {'vvelo-vor2.txt'}
    {'vvelo-vor3.txt'}
% row_col = 26
% figure
% hold on
% for k = 1:3
%     plot(uz{k}(:,row_col), uy{k}(:,row_col), DisplayName=filenameu{k})
% end
% hold off
% grid
% xlabel('U')
% ylabel('Y')
% title('''U'' Matrices')
% legend(Location='best')
% figure
% hold on
% for k = 1:3
%     plot(vx{k}(row_col,:), vz{k}(:,row_col), DisplayName=filenamev{k})
% end
% hold off
% grid
% xlabel('X')
% ylabel('V')
% title('''V'' Matrices')
% legend(Location='best')

.

Ruthra 2026-1-10，16:43

Star Strider 2026-1-10，17:14

You have a script named 'grid.m' that is overshadowing with the MATLAB grid function.

You need to rename your 'grid.m' to something that is different from any of the MATLAB built-in functions.

(I assume the files are being read, so 'u{:}' and 'v{:}' have data.)

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Help to plot a graph using the data file

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Help to plot a graph using the data file

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