Rescale an axis in other steps without creating vector

Hello,

I have the following problem: I have for example 1000 measurement points but in 0.02 second steps. In the plot I want to have not a scale from 0 to 1000 but from 0 to 20 (=1000*0.02). As I don't know the length of my data points, I cannot create a vector in 0.02 steps for the x-axis because then Matlab returns that the vectors must be the same lengths.

Is there a possibility, just to divide the x-axis by 50?

Thanks, Leo

Answer 1

[sixwwwwww]

You can control your x-axis by plotting your data against your time as follows:

y = rand(1, 1000); % your data
x = linspace(0, 0.02, numel(y)); % your time series
plot(x, y) % your plot of data against time series

or you can use 'xlim' for this purpose. see

doc xlim

for more information

Answer 2

[Leonard]

That's exactly my point: With this I can't do it.

I don't want the first 20 measurement points. I want to have all 1000 measurement points, but the x-axis shall contain the numbers 0 to 20 (instead of 0 to 1000).

I hope, you now get, what I mean. Thx

Answer 3

[sixwwwwww]

Try this:

y = rand(1, 1000); % your data
x = linspace(0, 20, numel(y)); % your time series
plot(x, y) % your plot of data against time series

It will plot 1000 points within range of 0 to 20

Answer 4

[Leonard]

OK, this wasn't the solution either but I found out a way for myself now. Looks like this (for your interest or anybody else who needs it):

plot(0.02:0.02:numel(y)/50,y)

y is the function.

[sixwwwwww]

whats the difference in your code and solution I provided? I am also generating the same values of x = 0.02 0.04 ...

you can run my code and then you can see workspace varaiable x for confirmation. Also I appreciate you in a way that you found it yourself as well and it is a better way of learning. Good luck!

[Leonard]

In your case you have determined that the length is 20 seconds. But in my case this value is variable. So sometimes it's 20 seconds, sometimes 50 seconds or whatever other value.

But I just figured out, that your way could be also possible if I just choose the end point as a variable as well like this:

x = linspace(0, numel(y)/50, numel(y));

Thanks for your help again!

[sixwwwwww]

In my case 20 is not fix. in the following line of code you can just replace 20 by any value then it will also work

x = linspace(0, 20, numel(y));

Good luck!