Open data in File as per user input

Hello, I am trying to get input from user to load a file and then ask which variable from the file would they like to plot. The input file will be a .mat file and it is a 1x1 struct file with various 2 double series data in it.

When I run this, the error says: Unrecognized field name "x"

Here is my code:

filename=input('Input File Name \n','s');
file = load(filename);
x=string(input('Variable? \n','s'));

plot(file.x)

Answer 1

[Walter Roberson]

plot(file.(x))