Plot parameter functions

Some parameters are provided as functions (e.g. diffusivity as a function of concentration and temperature). Currently, to plot them you have to do something like this

import pybamm

params = pybamm.ParameterValues(chemistry=pybamm.parameter_sets.Chen2020)
i0 = params["Negative electrode exchange-current density [A.m-2]"]
x = pybamm.linspace(3000,6000,100)
i0_eval = i0(1000,x,300)
i0_processed = params.process_symbol(i0_eval)
pybamm.plot(x, i0_processed)

We have to process the function “Negative electrode exchange-current density [A.m-2]” since its definition contains a pybamm.Parameter. It would be neat to be able to do something like params.plot("Negative electrode exchange-current density [A.m-2]", (1000, x, 300)) instead so you can quickly plot the functional dependence of parameters. We can use pybamm.plot and pybamm.plot2D to plot the resulting arrays.

Maybe you could pass a list or dict of parameter names and values so you can plot multiple parameters on the same plot.

[tinosulzer]

Just a comment - when we provide custom plotting functions we need to be careful not to do so at the expense of matplotlib flexibility (specifying args and kwargs in the plot, adding xlabel and ylabel and legend, etc).

[tinosulzer]

I see the issue now. What about editing the .evaluate() function so it can return an array?