#1465 allow evaluate parameter to return arrays

[rtimms]

Description

ParameterValues.evaluate() can now return arrays so that you can evaluate parameter functions as

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)
params.evaluate(i0(1000,x,300))

Also, plot and plot2D now take and return the axis ax for easier customization
.
Fixes #1465

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #1472 (cb04f46) into develop (b4735e1) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1472   +/-   ##
========================================
  Coverage    98.37%   98.37%           
========================================
  Files          282      282           
  Lines        16602    16602           
========================================
  Hits         16332    16332           
  Misses         270      270           

Impacted Files	Coverage Δ
pybamm/parameters/parameter_values.py	99.43% <100.00%> (ø)
pybamm/plotting/plot.py	100.00% <100.00%> (ø)
pybamm/plotting/plot2D.py	100.00% <100.00%> (ø)

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[valentinsulzer]

Looks great, thanks @rtimms ! @Saransh-cpp can you also edit the example in #1458 to use this?

[valentinsulzer]

just needs a changelog before merging

[Saransh-cpp]

Looks great, thanks @rtimms ! @Saransh-cpp can you also edit the example in #1458 to use this?

Yes, I will edit the example once this is merged.