store slices

[valentinsulzer]

Description

Store variable slices in the model after discretisation

Fixes #924

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

[brosaplanella]

So quick! Looks great Tino, thanks.

[codecov]

Codecov Report

Merging #925 into develop will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #925   +/-   ##
========================================
  Coverage    98.00%   98.00%           
========================================
  Files          208      208           
  Lines        10931    10936    +5     
========================================
+ Hits         10713    10718    +5     
  Misses         218      218           

Impacted Files	Coverage Δ
pybamm/discretisations/discretisation.py	99.76% <100.00%> (+<0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 13a0ca0...1d9bf54. Read the comment docs.