.. _tutorial:
Getting Started
***************

First we must import the library

.. code-block:: python

    import readparse as parse

To download a single element from the PARSE dataset (say, corresponding to SHARP 7821), use the :py:func:`readparse.pullPARSE` function. By default, this downloads it to a local directory.

.. code-block:: python

    parse.pullPARSE(7821,1)

Read the data with the :py:func:`readparse.readPARSE` function, which takes a tuple of the same arguments pullPARSE got.

.. code-block:: python

    data = parse.readPARSE((7821,1))

Now data is a :py:class:`readparse.PARSE` object, containing the full scattered data, which can be worked with as-is. Suppose we wish to visualize this element. It is easiest to do this if we first interpolate onto a regular grid, so let us do so.

.. code-block:: python

    data.compile_grid()

Now we'll trace some fieldlines for plotting.

.. code-block:: python

    import numpy as np

    xseed,yseed = np.meshgrid(np.linspace(0,max(data.nodes[:,0]),20),np.linspace(0,max(data.nodes[:,1]),20))
    seedpoints = np.vstack((xseed.ravel(),yseed.ravel(),np.zeros(20**2))).transpose()
    fieldlines = data.fieldlines(seedpoints)

Finally, we plot the fieldlines and lower boundary in vtk.

.. code-block:: python

    import pyvista as pv
    
    pl = pv.Plotter()
    Zmesh = pv.ImageData()
    Zmesh.dimensions = np.array([len(data.Bgrid.xcoords),
                                 len(data.Bgrid.ycoords),
                                 len(data.Bgrid.zcoords)])+1
    Zmesh.spacing = data.Bgrid.grid_spacing
    Zmesh.cell_data["values"] = data.Bgrid.vectors[:,:,:,2].ravel("F")
    pl.add_mesh(Zmesh.slice(normal=[0,0,1],origin=[1e-2,1e-2,1e-2]))
    for stream in fieldlines:
        pl.add_lines(stream,color='black',width=1,connected = True)
    pl.show()

.. raw:: html

   <iframe src="../_static/vtkwidget.html" height="345px" width="100%"></iframe>