How can I take the derivative of data from a .csv file and store it in a table?

I am trying to calculate acceleration from time and velocity using the code:

x=readtable('Drive Cycles EPA urban full.csv');
V=x(:,2)
T=x(:,1)
A=gradient(V(:))/gradient(T(:))

I have also tried diff instead of gradient. They both return the error:

Error using test (line 4)
Subscripting a table using linear indexing (one subscript) or multidimensional indexing (three or more subscripts) is not
supported. Use a row subscript and a variable subscript.

Any suggestions would be a huge help.

Thank you!

Answer 1

[Cris LaPierre]

x is a table already. Therefore, V and T are also tables.

See this doc page on accessing data in a table. Basically, to do what you are trying to do, you need to use curly braces.

V=x{:,2}
T=x{:,1}

Assuming your table variables are var1 and var2, you could also do the following

V=x.var2
T=x.var1

Finally, you might find it more helpful to use meaningful variable names.

x.Properties.VariableNames = {'T','V'};
A=gradient(x.V)/gradient(x.T)

[Justin Hollis]

Thanks for your help!

[Douglas Novaes]

Perfect!

Thank you.