How to graph this text file

I was trying to graph this text file, it keeps on giving me index must not exceed array bounds error, please help thank you.

clc
clear all

A = fopen('c1s1.txt','rt');

time = A(:,2);
encode1 = A(:,3);

plot(time,encode1)

title('Time vs Encoder 1 PoS')

Answer 1

[Star Strider]

The ‘A’ variable is actually the assigned file identification number, always a scalar. It us used to refer to the file using fscanf, textscan, or certain other file import functions.

Your code needs to read the file. Here is one way to do it, there are several others —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/982340/c1s1.txt', 'VariableNamingRule','preserve')

T1 = 1807×5 table
       Var1       Var2    Var3      Var4        Var5   
    __________    ____    _____    ______    __________

    {'['     }      0         0    927.47    {'0.000;'}
    {0×0 char}      1     0.004    927.47    {'0.000;'}
    {0×0 char}      2     0.009    927.47    {'0.000;'}
    {0×0 char}      3     0.013    927.47    {'0.000;'}
    {0×0 char}      4     0.018    927.47    {'0.000;'}
    {0×0 char}      5     0.022    927.47    {'0.000;'}
    {0×0 char}      6     0.027    927.47    {'0.000;'}
    {0×0 char}      7     0.031       926    {'0.000;'}
    {0×0 char}      8     0.035       926    {'0.000;'}
    {0×0 char}      9      0.04       926    {'0.000;'}
    {0×0 char}     10     0.044       926    {'0.000;'}
    {0×0 char}     11     0.049       926    {'0.000;'}
    {0×0 char}     12     0.053       926    {'0.000;'}
    {0×0 char}     13     0.058    925.44    {'0.000;'}
    {0×0 char}     14     0.062    925.28    {'0.000;'}
    {0×0 char}     15     0.066    925.12    {'0.000;'}

% Q1 = T1(end-10:end,:)

time = T1{:,2};
encode1 = T1{:,3};

figure
plot(time,encode1)
xlabel('Time')
ylabel('Encoder 1 PoS')
title('Time vs Encoder 1 PoS')

Var4 = T1{:,4};

figure
plot(time, Var4)
xlabel('Time')
ylabel('Var_4')

Plotting ‘Var4’ (that I did just to see what it was) is a bit more interesting.

.

[Kevin Antony]

thank you so much, appreciate it a lot ,so the variable A was the component causing the issue?

[Star Strider]

As always, my pleasure!

Variable ‘A’ was exactly what it was supposed to be, that being the file identification number. It just needed to be used to read the file, and that is easier (especially with this file) with readtable (although readmatrix would have worked as well, I generally use readtable because it displays the header information as variable names, helping me understand what’s in the file).

[Kevin Antony]

very sorry to distrub again, but as i am trying to graph this MATLAB says it cannot find the file, check path or permissions, i regrouped everything into MATLAB drive but still cannot get it to read, thank you

[Kevin Antony]

nevermind i figured it out, thank you so much for all the help

[Star Strider]

No worries!

That depends on where you‘re trying to access it.

Accessing it here is straightforward:

M1 = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/982340/c1s1.txt')

M1 = 1807×5

NaN 0 0 927.4690 NaN NaN 1.0000 0.0040 927.4690 NaN NaN 2.0000 0.0090 927.4690 NaN NaN 3.0000 0.0130 927.4690 NaN NaN 4.0000 0.0180 927.4690 NaN NaN 5.0000 0.0220 927.4690 NaN NaN 6.0000 0.0270 927.4690 NaN NaN 7.0000 0.0310 926.0000 NaN NaN 8.0000 0.0350 926.0000 NaN NaN 9.0000 0.0400 926.0000 NaN

That should also work from your computer, so long as you’re connected to the Internet.

The NaN values (that do not appear as such in the table) are due to their not being numeric.

If you want to read it on your computer, MATLAB has to know where it is. If it’s on your MATLAB path, the full path can be obtained by:

fulpath = which('c1s1.txt')

Otherwise, you need to put it on your MATLAB path (see What Is the MATLAB Search Path?) or use the fullfile function to create a path to it.

Also, I believe the correct plot should be:

figure
plot(M1(:,3), M1(:,4))
grid

.