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https://github.com/xarray-contrib/xarray-simlab

Xarray extension and framework for computer model simulations
https://github.com/xarray-contrib/xarray-simlab

modelling python simulation-framework xarray

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Xarray extension and framework for computer model simulations

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xarray-simlab: xarray extension for computer model simulations
==============================================================

|Build Status| |Coverage| |Doc Status| |Zenodo|

xarray-simlab is a Python library that provides both a generic
framework for building computational models in a modular fashion and a
xarray_ extension for setting and running simulations using the
xarray's ``Dataset`` structure. It is designed for fast, interactive
and exploratory modeling.

xarray-simlab is well integrated with other libraries of the PyData
ecosystem such as `dask `_ and `zarr
`_.

.. _xarray: http://xarray.pydata.org
.. |Build Status| image:: https://github.com/xarray-contrib/xarray-simlab/workflows/test/badge.svg?branch=master
:target: https://github.com/xarray-contrib/xarray-simlab/actions?workflow=test
:alt: Build Status
.. |Coverage| image:: https://codecov.io/gh/xarray-contrib/xarray-simlab/branch/master/graphs/badge.svg?branch=master
:target: https://codecov.io/github/xarray-contrib/xarray-simlab?branch=master
:alt: Coverage Status
.. |Doc Status| image:: http://readthedocs.org/projects/xarray-simlab/badge/?version=latest
:target: http://xarray-simlab.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status
.. |Zenodo| image:: https://zenodo.org/badge/93938479.svg
:target: https://zenodo.org/badge/latestdoi/93938479
:alt: Citation

In a nutshell
-------------

The Conway's Game of Life example shown below is adapted from this
`blog post `_
by Jake VanderPlas.

1. Create new model components by writing compact Python classes,
i.e., very much like dataclasses_:

.. code-block:: python

import numpy as np
import xsimlab as xs

@xs.process
class GameOfLife:
world = xs.variable(
dims=('x', 'y'), intent='inout', encoding={'fill_value': None}
)

def run_step(self):
nbrs_count = sum(
np.roll(np.roll(self.world, i, 0), j, 1)
for i in (-1, 0, 1) for j in (-1, 0, 1)
if (i != 0 or j != 0)
)
self._world_next = (nbrs_count == 3) | (self.world & (nbrs_count == 2))

def finalize_step(self):
self.world[:] = self._world_next

@xs.process
class Glider:
pos = xs.variable(dims='point_xy', description='glider position')
world = xs.foreign(GameOfLife, 'world', intent='out')

def initialize(self):
x, y = self.pos

kernel = [[1, 0, 0],
[0, 1, 1],
[1, 1, 0]]

self.world = np.zeros((10, 10), dtype=bool)
self.world[x:x+3, y:y+3] = kernel

2. Create a new model just by providing a dictionary of model components:

.. code-block:: python

model = xs.Model({'gol': GameOfLife,
'init': Glider})

3. Create an input ``xarray.Dataset``, run the model and get an output
``xarray.Dataset``:

.. code-block:: python

input_dataset = xs.create_setup(
model=model,
clocks={'step': np.arange(9)},
input_vars={'init__pos': ('point_xy', [4, 5])},
output_vars={'gol__world': 'step'}
)

output_dataset = input_dataset.xsimlab.run(model=model)

.. code-block:: python

>>> output_dataset

Dimensions: (point_xy: 2, step: 9, x: 10, y: 10)
Coordinates:
* step (step) int64 0 1 2 3 4 5 6 7 8
Dimensions without coordinates: point_xy, x, y
Data variables:
init__pos (point_xy) int64 4 5
gol__world (step, x, y) bool False False False False ... False False False

4. Perform model setup, pre-processing, run, post-processing and
visualization in a functional style, using method chaining:

.. code-block:: python

import matplotlib.pyplot as plt

with model:
(input_dataset
.xsimlab.update_vars(
input_vars={'init__pos': ('point_xy', [2, 2])}
)
.xsimlab.run()
.gol__world.plot.imshow(
col='step', col_wrap=3, figsize=(5, 5),
xticks=[], yticks=[],
add_colorbar=False, cmap=plt.cm.binary)
)

.. image:: doc/_static/gol.png
:width: 400px

.. _dataclasses: https://docs.python.org/3/library/dataclasses.html

Documentation
-------------

Documentation is hosted on ReadTheDocs:
http://xarray-simlab.readthedocs.io

License
-------

3-clause ("Modified" or "New") BSD license,
see `License file `__.

xarray-simlab uses short parts of the code of the xarray_, pandas_ and
dask_ libraries. Their licenses are reproduced in the "licenses"
directory.

.. _pandas: http://pandas.pydata.org/

Acknowledgment
--------------

This project is supported by the `Earth Surface Process Modelling`_
group of the GFZ Helmholtz Centre Potsdam.

.. _`Earth Surface Process Modelling`: http://www.gfz-potsdam.de/en/section/earth-surface-process-modelling/

Citation
--------

If you use xarray-simlab in a scientific publication, we would
appreciate a `citation`_.

.. _`citation`: http://xarray-simlab.readthedocs.io/en/latest/citation.html