MATLAB: How to read this txt.data in matlab

graphtxt

I'm searching for answer that can read this data in matlab.

Since this dataset's variables are departed with colon, I can't read this files in matrix.

I want to put data 1 in x coordinate, and data 2 in y coordinate.

To show this data in 2D, I want to put only two data which are departed in colon.

To show this data in 3D, I want to put all three data in 3 Dimension graph.

Best Answer

Use the textscan function to read it:

fidi = fopen('data-ex1.txt');
Dc = textscan(fidi, '%f 1:%f 2:%f', 'CollectOutput',1);
D = cell2mat(Dc);
figure(1)
plot(D(:,2), D(:,3))
grid
title('2D Plot')
figure(2)
plot3(D(:,1), D(:,2), D(:,3))
grid on
title('3D Plot')
xlabel('X')
ylabel('Y')
zlabel('Z')

The ‘D’ matrix has the numeric results. I assume you do not want the ‘1:’ and ‘2:’, so the format string in the textscam call eliminates them when in reads the file. The ‘1:’ values are ‘D(:,2)’, and the ‘2:’ values are ‘D(:,3)’. The column of ±1 are in ‘D(:,1)’.

Change the plots to produce the result you want.

Related Solutions

MATLAB: Plotting multiple series on one graph from a text file

They all appear to plot together, and there is no easy way to offset them to plot them in a single plot. The best option then appears to be plotting them each in a subplot:

fidi = fopen('carpos.txt','rt');
Dc = textscan(fidi, '%f%f%f', 'CollectOutput',1);
D = cell2mat(Dc);
endData = find(D(:,1) == 14, 1, 'last');
D = D(1:endData,:);
Dr = reshape(D, 15, 3, []);
figure
for k1 = 1:size(Dr,1)
    subplot(5,3,k1)
    plot3(squeeze(Dr(k1,1,:)), squeeze(Dr(k1,2,:)), squeeze(Dr(k1,3,:)))
    grid on
    axis equal
    title(sprintf('%d',k1-1))
end

Experiment to get the result you want.

MATLAB: Plotting The bodee plots extracted from LTSPICE simulator

MATLAB can read it, however it needs a bit of help in order to understand how to read it.

Try this:

fidi = fopen('Data.txt');
Dc = textscan(fidi, '%f(%fdB,%f°)', 'CollectOutput',1);
D = cell2mat(Dc);
figure
subplot(2,1,1)
plot(D(:,1), D(:,2))
title('Amplitude (dB)')
grid
subplot(2,1,2)
plot(D(:,1), D(:,3))
title('Phase (°)')
grid
xlabel('Frequency')

The frequency appears to be ‘D(:,1)’, amplitude ‘D(:,2)’, and phase ‘D(:,3)’ in my code. That reads the file correctly, and seems to produce the correct plot. See the documentation on textscan (link) to understand how it works and what my code does.

Experiment to get the result you want.

EDIT — (18 Apr 2019 at 11:22)

The plot calls can be improved slightly as:

figure
subplot(2,1,1)
semilogx(D(:,1), D(:,2))
ylabel('Amplitude (dB)')
grid
subplot(2,1,2)
semilogx(D(:,1), D(:,3))
ylabel('Phase (°)')
grid
xlabel('Frequency')

NOTE: Tthe frequency units are not stated in your file, so it is not possible to determine if they are Hz or rad/sec. The amplitude is clearly in dB so it is already log-transformed, and the phase is clearly in degrees (°).

Best Answer

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MATLAB: Plotting multiple series on one graph from a text file

MATLAB: Plotting The bodee plots extracted from LTSPICE simulator

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