Plot X, Y, Z axes with respect to time

So I have a file which contains the accelerometer values of a phone. The CSV file contains time, x, y and z columns. I am trying to find a way to plot the 3 axes (x, y and z) vs. time into one graph rather than using 'stackedplot'. How would one go about this?

Answer 1

[Voss]

% making up some data:
t = 0:0.01:10;
x = cos(t);
y = sin(t);
z = t;

% plot x,y,z vs t in one plot:
figure();
plot(t,x,t,y,t,z);
legend('x','y','z');
xlabel('t');
grid on

% or make a 3d line whose points are (x,y,z):
figure();
plot3(x,y,z);
xlabel('x');
ylabel('y');
zlabel('z');
box on
grid on

[Navin Johnson]

Hi! Thank you so much for your answer. I am looking for something like the first graph you had there.

[Voss]

You're welcome!

Let me know if you have any questions about that first plot. Otherwise, if it makes sense, please mark the answer as 'Accepted' to close out the question. Thanks!

[Navin Johnson]

Hi the only issue I have is that my x, y and z values are of the "table" type. Plot doesn't work for table and they suggest using "stackedplot" which works but I would prefer one graph. This is the error I am getting:

Error using tabular/plot (line 220)

Tables and timetables do not have a plot method. To plot a table or a timetable, use the stackedplot function. As an alternative,extract table or timetable variables using dot or brace subscripting, and then pass the variables as input arguments to the plot function.

The code I implemented:

%Load all the Data

backside_accel = readtable('Lab5-Phone-BackSide/accelerometer.csv');

t = 0:0.1:4;

x_back_accel = backside_accel(:,1);

y_back_accel = backside_accel(:,2);

z_back_accel = backside_accel(:,3);

figure()

plot(t,x_back_accel,t,y_back_accel,t,z_back_accel);

[Voss]

Use curly brace {} indexing, and make sure the t you define there is appropriate for your table (t has to have the same number of elements as your table backside_accel has rows):

backside_accel = readtable('Lab5-Phone-BackSide/accelerometer.csv');
t = 0:0.1:4;
% x_back_accel = backside_accel(:,1);
% y_back_accel = backside_accel(:,2);
% z_back_accel = backside_accel(:,3);
x_back_accel = backside_accel{:,1};
y_back_accel = backside_accel{:,2};
z_back_accel = backside_accel{:,3};
figure()
plot(t,x_back_accel,t,y_back_accel,t,z_back_accel);

[Navin Johnson]

In my csv there are 30+ observations which were collected for a 3 second span. So how would I distribute t?

[Voss]

t = linspace(0,3,height(backside_accel));

[Navin Johnson]

Hi! Thank you so much for your time and answers! It works!

[Voss]

Excellent! You're welcome!

Answer 2

[VBBV]

x_back_accel = cell2mat(backside_accel(:,1));
y_back_accel = cell2mat(backside_accel(:,2));
z_back_accel = cell2mat(backside_accel(:,3));
plot(t,x_back_accel,t,y_back_accel,t,z_back_accel);

Convert them to double array and plot it.

[Navin Johnson]

Hi! Thank you for your answer! I did want to confirm that the variable t is defined in the range I specified correct?

[VBBV]

Check the size of variable t and that of other variables you are plotting e.g. x_back_accel. They need to be of same length. Othwerwise you get vector length error using plot

[Navin Johnson]

Yeah that makes sense. Plus I tried out your method but it gave me an error like:

Error using cell2mat (line 42)

Subscripting into a table using one subscript (as in t(i)) is not supported. Specify a row subscript and a variable subscript, as

in t(rows,vars). To select variables, use t(:,i) or for one variable t.(i). To select rows, use t(i,:).

Error in ENGO585_Lab5 (line 18)

x_back_accel = cell2mat(backside_accel(:,1));

I think I'm gonna use stackedplot instead. I appreciate your time!

[VBBV]

You can use readmatrix function instead of readtable when importing data and to plot them using your initial code without having to use cell2mat

backside_accel = readmatrix('Lab5-Phone-BackSide/accelerometer.csv');
t = 0:0.1:4;
x_back_accel = backside_accel(:,1);
y_back_accel = backside_accel(:,2);
z_back_accel = backside_accel(:,3);
figure()
plot(t,x_back_accel,t,y_back_accel,t,z_back_accel);

[Navin Johnson]

Oooh I'll try that