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DOCS: Create a short tutorial about writing basic python + simplnx in…
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…tegration

Signed-off-by: Michael Jackson <[email protected]>
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imikejackson committed Apr 26, 2024
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make clean
make html
```

## Restructured Text Heading Levels

=====================================
Page Title
=====================================

###################################
Part Title
###################################

Heading 1
=========

Heading 2
---------

Heading 3
^^^^^^^^^

Heading 4
""""""""""


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compiling additional plugins, and you want the python docs
generated, you will need to add those to the list below
DREAM3D-NX Python Docs (v1.2.7)
DREAM3D-NX Python Docs (v1.3.0)
=================================

Installation
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Overview
DataObjects
Geometry
Reference_Frame_Notes

.. toctree::
:maxdepth: 2
:caption: Using SIMPLNX in Python

Python_Introduction
User_API
Reference_Frame_Notes
Tutorial_1

.. toctree::
:maxdepth: 1
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.. Tutorial 1:
=====================================
Tutorial 1: Basic Python Integration
=====================================

###################################
Anaconda Virtual Environment Setup
###################################

.. code:: shell
conda config --add channels conda-forge
conda config --set channel_priority strict
conda create -n nxpython python=3.12
conda activate nxpython
conda install -c bluequartzsoftware dream3dnx
###################################
Introduction
###################################

Setup your virtual environment following the directions from above. Then create a Tutorial_1.py file anywhere that you want and open that up in your Editor/IDE.


###################################
Necessary Import Statements
###################################

Just about every python source code that is written will need the following import Statements:

.. code:: python
import simplnx as nx
import numpy as np
If you will be using filters from DREAM3D-NX's other plugins, then you may additionally need the following:

.. code:: python
import itkimageprocessing as nxitk
import orientationanalysis as nxor
###################################
Creating the DataStructure Object
###################################

If you will be interacting with data stored in DREAM3D-NX, you will need to instantiate a :ref:`DataStructure` object. This is
simply done with the following line of code:

.. code:: python
# Create the DataStructure Object
data_structure = nx.DataStructure()
A few caveats to take note of:
1. You can have as many :ref:`DataStructure` objects as you want/need. Typically all data is stored in a single DataStructure object but there are use cases where having more than a single :ref:`DataStructure` object is needed.
2. Only a **single** :ref:`DataStructure` object can be stored in a .dream3d file.


################################################
First Steps: Create a Group in the DataStructure
################################################

As in the user interface of DREAM3D-NX, you as the developer can execute any of filter from DREAM3D-NX using only Python codes. This is performed
by instantiating the filter and then calling the `execute()` method with the appropriate parameters used in the call. With the current API, we are tending to
inline instantiate the filter and execute it all in the same line. Some things to note with this small piece of code:

- There will **always** be a required :ref:`DataStructure` object. All arguments in the `execute()` method are named arguments. None are positional. This means that each argument must be in the form of 'name=value'.
- The 2nd argument shows an use of the :ref:`DataPath` object. Lots of filters will require a :ref:`DataPath` object so this is a common use.
- There is a method called `hierarchy_to_str()` that is a part of the :ref:`DataStructure` class which will print the heirarchy of the DataStructure.


.. code:: python
result = nx.CreateDataGroup.execute(data_structure=data_structure,
data_object_path=nx.DataPath("Top Level Group"))
print(f'{data_structure.hierarchy_to_str()}')
If we were to run this code we would get the following:

.. code:: text
|--Top Level Group
Let's try to add a bunch of groups to the :ref:`DataStructure` object by using a loop:

.. code:: python
for i in range(1, 6):
current_data_group_path = nx.DataPath(f"Top Level Group {i}")
result = nx.CreateDataGroup.execute(data_structure=data_structure,
data_object_path=current_data_group_path)
print(f'{data_structure.hierarchy_to_str()}')
And the output would look like the following:

.. code:: text
|--Top Level Group 1
|--Top Level Group 2
|--Top Level Group 3
|--Top Level Group 4
|--Top Level Group 5
################################################
Result Objects
################################################

Each time a filter is executed, it will return an `nx.ExecuteResult` object. This
object can be interrogated for both warnings and errors that occured while the
filter was executing. A typical function that can be written to properly error
check the 'result' value is the following:

.. code:: python
def check_filter_result(filter: nx.IFilter, result: nx.IFilter.ExecuteResult) -> None:
"""
This function will check the `result` for any errors. If errors do exist then a
`RuntimeError` will be thrown. Your own code to modify this to return something
else that doesn't just stop your script in its tracks.
"""
if len(result.warnings) != 0:
for w in result.warnings:
print(f'Warning: ({w.code}) {w.message}')
has_errors = len(result.errors) != 0
if has_errors:
for err in result.errors:
print(f'Error: ({err.code}) {err.message}')
raise RuntimeError(result)
print(f"{filter.name()} :: No errors running the filter")
If you were to integrate this into your own code, then we would get the following when we wanted to execute a filter:

.. code:: python
result = nx.CreateDataGroup.execute(data_structure=data_structure,
data_object_path=nx.DataPath("Top Level Group"))
check_filter_result( nx.CreateDataGroup(), result)
################################################
Creating a DataArray Object
################################################

Raw data is stored in a :ref:`DataArray` object within the :ref:`DataStructure`. The DREAM3D-NX python bindings only expose a subset of functionality
from the :ref:`DataArray`, enough to get the name, tuple shape and component shape. **ALL** interactions to modify a :ref:`DataArray` are done via a
`numpy view <https://numpy.org/doc/stable/user/basics.copies.html>`_. Let us first create a :ref:`DataArray` object within the :ref:`DataStructure` by using the
:ref:`CreateDataArray` filter. Adding into the current python source file...

.. code:: python
result = nx.CreateDataArray().execute(data_structure=data_structure,
component_count=1,
initialization_value_str="0",
numeric_type_index=nx.NumericType.float32,
output_array_path=nx.DataPath("Top Level Group/2D Array"),
tuple_dimensions=[[5,4]])
nxutility.check_filter_result( nx.CreateDataArray(), result)
print(f'{data_structure.hierarchy_to_str()}')
Note how we are creating the array inside the very first :ref:`DataGroup` that we created. If we run the file from start to finish we now get the following output:

.. code:: text
|--Top Level Group
|--2D Array
|--Top Level Group 1
|--Top Level Group 2
|--Top Level Group 3
|--Top Level Group 4
|--Top Level Group 5
As you can see we have successfully created an array that can hold some data. The next step is to interact with that :ref:`DataArray` and use numpy to modify the array in place.

################################################
Modifying the DataArray Object using Numpy
################################################

The method from :ref:`DataStructure` that we will be using is item selection using the '[]' operator paired with an
immediate call to the '.npview()' method. This will retrieve the a numpy view of the DataArray that was created in the last step.

.. code:: python
array_view = data_structure["Top Level Group/2D Array"].npview()
Now that we have a numpy view we can do anything to the array that numpy (or any other package that accepts numpy views) can do for us. For example, we can
create random data in the array using the following:

.. code:: python
# Fill the numpy data view with random numbers
rng = np.random.default_rng()
rng.standard_normal(out=array_view, dtype=np.float32)
print(f'{array_view}')
The output from this code would print something similar to:

.. code:: text
[[[-1.3746183 ]
[-0.08409024]
[ 1.2792562 ]
[-0.37265882]
[ 0.05201177]]
[[-0.11597582]
[-0.35329401]
[-0.88307136]
[-0.98040694]
[ 0.28385338]]
[[ 0.7635286 ]
[-1.3911186 ]
[ 0.5670461 ]
[ 0.11915083]
[-0.8656706 ]]
[[ 2.1133974 ]
[ 1.3168721 ]
[ 2.6951575 ]
[ 0.10712756]
[-0.07898012]]]
And if you wanted to use `matplotlib <https://matplotlib.org/>`_ to view the data, that is easily done in the usual manner:

.. code:: python
# Show the result
plt.imshow(array_view)
plt.title("Random Data")
plt.axis('off') # to turn off axes
plt.show()
.. figure:: Images/Tutorial_1_Image_1.png
:alt: MatPlotLib output


################################################
Complete Source Code
################################################

.. code:: python
import simplnx as nx
import numpy as np
import matplotlib.pyplot as plt
import nxutility
# Create the DataStructure instance
data_structure = nx.DataStructure()
result = nx.CreateDataGroup.execute(data_structure=data_structure,
data_object_path=nx.DataPath("Top Level Group"))
# Loop to create a bunch of DataGroups.
for i in range(1, 6):
current_data_group_path = nx.DataPath(f"Top Level Group {i}")
result = nx.CreateDataGroup.execute(data_structure=data_structure,
data_object_path=current_data_group_path)
# Execute the filter
result = nx.CreateDataArray().execute(data_structure=data_structure,
component_count=1,
initialization_value_str="0",
numeric_type_index=nx.NumericType.float32,
output_array_path=nx.DataPath("Top Level Group/2D Array"),
tuple_dimensions=[[4,5]])
nxutility.check_filter_result( nx.CreateDataArray(), result)
print(f'{data_structure.hierarchy_to_str()}')
# Try to get the array from the DataStructure
try:
array_view = data_structure["Top Level Group/2D Array"].npview()
except AttributeError as attrerr:
print(f'{attrerr}')
quit(1) # This is pretty harsh! Maybe something more elegant to unwind from this error
# Fill the numpy data view with random numbers
rng = np.random.default_rng()
rng.standard_normal(out=array_view, dtype=np.float32)
print(f'{array_view}')
# Show the result
plt.imshow(array_view)
plt.title("Random Data")
plt.axis('off') # to turn off axes
plt.show()

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