Import data from text file

I have a text files with two colums, when I used the

importfile(Data_Chan1.txt);

data=Data_Chan1(2:end,1:2);

I get error in reading the data.

[Walter Roberson]

Have you experimented with readtable() ?

[Ali Agha]

no, I just changed the Data_Chan1 to the path of the data but received another error saying (Invalid first data argument).

[Ali Agha]

when put the mouse on the data lines I see it read Data:0x2 empty char array

[Ali Agha]

I have this sample of the data

[Ive J]

You need to mung your txt file, first few lines are totally messed up. Maybe you manually modified it (?).

doc readtable
doc readmatrix
doc readlines % to get a feel on your data structure 

Answer 1

[Kevin Holly]

I used the import data button on the toolstrip to import the text file. Then I generated the function below.

DataChan1 = importDataChanfile('Data_Chan1.txt');
size(DataChan1)

ans = 1×2

90112 2

data=DataChan1(2:end,1:2);
size(data)

ans = 1×2

90111 2

data

data = 90111×2 table
       Time       Amplitude 
    __________    __________

    0.00019531    2.8167e-05
    0.00039063    2.8191e-05
    0.00058594    2.8337e-05
    0.00078125    2.8255e-05
    0.00097656    2.7935e-05
     0.0011719    2.7522e-05
     0.0013672    2.7267e-05
     0.0015625    2.7049e-05
     0.0017578    2.6771e-05
     0.0019531    2.6771e-05
     0.0021484    2.6546e-05
     0.0023437    2.6159e-05
     0.0025391    2.6179e-05
     0.0027344    2.5608e-05
     0.0029297    2.4605e-05
      0.003125    2.3894e-05

plot(data.Time,data.Amplitude)

 function DataChan1 = importDataChanfile(filename, dataLines)
%IMPORTFILE Import data from a text file
%  DATACHAN1 = IMPORTFILE(FILENAME) reads data from text file FILENAME
%  for the default selection.  Returns the data as a table.
%
%  DATACHAN1 = IMPORTFILE(FILE, DATALINES) reads data for the specified
%  row interval(s) of text file FILENAME. Specify DATALINES as a
%  positive scalar integer or a N-by-2 array of positive scalar integers
%  for dis-contiguous row intervals.
%
%  Example:
%  DataChan1 = importfile("C:\Users\kevinh\OneDrive - MathWorks\Desktop\Data_Chan1.txt", [19, Inf]);
%
%  See also READTABLE.
%
% Auto-generated by MATLAB on 14-Jan-2022 13:29:17

%% Input handling

% If dataLines is not specified, define defaults
if nargin < 2
    dataLines = [19, Inf];
end

%% Set up the Import Options and import the data
opts = delimitedTextImportOptions("NumVariables", 2);

% Specify range and delimiter
opts.DataLines = dataLines;
opts.Delimiter = "\t";

% Specify column names and types
opts.VariableNames = ["Time", "Amplitude"];
opts.VariableTypes = ["double", "double"];

% Specify file level properties
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";

% Import the data
DataChan1 = readtable(filename, opts);

end

[Ali Agha]

Thank you Kevin, it's really helpful to solve the issue but I'm still facing problem in running the data into the script below: appreciate if you can check it. For many days not able to identify the problem.

close all;clear;clc;
% Data_Chan1.txt --- x-dirention displacement signal
% Data_Chan2.txt --- y-dirention displacement signal
% Data_Chan3.txt --- y-acceleration signal
% Data_Chan4.txt --- z-acceleration signal
% modify the path to the file to be analysed
path = 'rub-impact/group1/900rpm/Throughput/Data_Chan1.txt');
time=DataChan1(:,1); % time sequency
x=DataChan1(:,2); % displacement signal sequency (x, y, or keyphasor, here is x)
fs=10240;    % samling freuency
% plot time waveform
figure
plot(t,x)
% plot spectrum
figure
plotfft(x,fs,'b')
% modify the path to the file to be analysed
path_2=load('rub-impact/group1/900rpm/Throughput/Data_Chan2.txt');
data=path(2:end,1:2);
t=data(:,1); % time sequency
y=data(:,2); % displacement signal sequency (x, y, or keyphasor, here is y)
% plot time waveform
figure
plot(t,y)
% plot spectrum
figure
plotfft(y,fs,'b')
% modify the path to the file to be analysed
path_3=load('rub-impact/group1/900rpm/Throughput/Data_Chan3.txt');
data=path_3(2:end,1:2);
t=data(:,1); % time sequency
y=data(:,2); % displacement signal sequency (x, y, or keyphasor, here is y)
% plot time waveform
figure
plot(t,y)
% plot spectrum
figure
plotfft(y,fs,'b')
% modify the path to the file to be analysed
path_4=load('rub-impact/group1/900rpm/Throughput/Data_Chan4.txt');
data=path_4(2:end,1:2);
t=data(:,1); % time sequency
z=data(:,2); % displacement signal sequency (x, y, z or keyphasor, here is z)
% plot time waveform
figure
plot(t,z)
% plot spectrum
figure
plotfft(z,fs,'b')
% plot keyphasor signal
path=load('rub-impact/group1/900rpm/Throughput/Data_Chan1.txt'); 
keyphasor=path(:,2); % displacement signal sequency (x, y, or keyphasor, here is keyphasor)
figure
plot(t,keyphasor)
% plot the orbit
path=load('rub-impact/group1/900rpm/Throughput/Data_Chan2.txt');
y=data(:,2); % displacement signal sequency (x, y, or keyphasor, here is y)
figure
plot(x,y)

[Kevin Holly]

close all;clear;clc;

% Data_Chan1.txt --- x-dirention displacement signal
% Data_Chan2.txt --- y-dirention displacement signal
% Data_Chan3.txt --- y-acceleration signal
% Data_Chan4.txt --- z-acceleration signal
% modify the path to the file to be analysed


DataChan1 = importDataChanfile('Data_Chan1.txt');

% Alternatively, you can the command below to select the file
% filename = uigetfile;
% DataChan1 = filename

% path = 'rub-impact/group1/900rpm/Throughput/Data_Chan1.txt');
time=table2array(DataChan1(:,1)); % time sequency
x=table2array(DataChan1(:,2)); % displacement signal sequency (x, y, or keyphasor, here is x)
fs=10240;    % sampling freuency

% plot time waveform
figure
plot(time,x) %change t to time
xlabel('Time')
ylabel('Displacement Signal Sequency')

% plot keyphasor signal
keyphasor=table2array(DataChan1(:,2)); % displacement signal sequency (x, y, or keyphasor, here is keyphasor)

figure
plot(time,keyphasor)

% plot spectrum
figure
pspectrum(x,fs) % plotfft(x,fs,'b')

% Import DataChan2
DataChan2 = importDataChanfile('Data_Chan2.txt');
% 
% % modify the path to the file to be analysed
% path_2=load('rub-impact/group1/900rpm/Throughput/Data_Chan2.txt');
data=DataChan2(2:end,1:2);
t=table2array(data(:,1)); % time sequency
y=table2array(data(:,2)); % displacement signal sequency (x, y, or keyphasor, here is y)

% plot time waveform
figure
plot(t,y)

% plot spectrum
figure
pspectrum(y,fs)

% plot the orbit
figure
plot(x,y(1:length(x)))

% Import DataChan3
DataChan3 = importDataChanfile('Data_Chan3.txt');

data=DataChan3(2:end,1:2);
t=table2array(data(:,1)); % time sequency
y=table2array(data(:,2)); % displacement signal sequency (x, y, or keyphasor, here is y)

% plot time waveform
figure
plot(t,y)

% plot spectrum
figure
pspectrum(y,fs)

% Import DataChan4
DataChan4 = importDataChanfile('Data_Chan4.txt');

data=DataChan4(2:end,1:2);
t=table2array(data(:,1)); % time sequency
z=table2array(data(:,2)); % displacement signal sequency (x, y, or keyphasor, here is y)

% plot time waveform
figure
plot(t,z)

% plot spectrum
figure
pspectrum(z,fs)