.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "gallery/01_getting_started/p03_loading_data.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code. .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_01_getting_started_p03_loading_data.py: Loading and Plotting MHD Data ============================== This example introduces the two steps needed to go from a PSI data file to a rendered scene: 1. **Fetching a dataset** — :func:`~pyvisual.utils.data.fetch_datasets` downloads (or retrieves from cache) a version-pinned HDF5 file from the PSI asset server and returns its local path. 2. **Reading the data** — :func:`~psi_io.psi_io.read_hdf_by_index` loads the array values and the three coordinate grids :math:`(r, \theta, \phi)` from the file. Passing ``None`` for a dimension selects its full extent; passing an integer index fixes that dimension to a single grid point. The dataset used here is the radial magnetic field :math:`B_r` from a Thermo 2 steady-state coronal simulation for Carrington Rotation 2282 (CR 2282), covering the domain :math:`r \in [1,\,30]\,R_\odot`. .. GENERATED FROM PYTHON SOURCE LINES 20-25 .. code-block:: Python from psi_io import read_hdf_by_index from pyvisual import Plot3d from pyvisual.utils.data import fetch_datasets .. GENERATED FROM PYTHON SOURCE LINES 26-35 Fetching a Dataset ------------------ :func:`~pyvisual.utils.data.fetch_datasets` accepts a *domain* identifier (``'cor'`` for the coronal domain, ``'hel'`` for heliospheric) and a *variable* name. It returns a :func:`~collections.namedtuple` whose fields are named ``"{domain}_{variable}"``. The first call downloads the file to the local cache; subsequent calls return the cached copy immediately without hitting the network. .. GENERATED FROM PYTHON SOURCE LINES 35-39 .. code-block:: Python datasets = fetch_datasets("cor", "br") br_file = datasets.cor_br .. GENERATED FROM PYTHON SOURCE LINES 40-55 Reading a 2-D Radial Slice -------------------------- :func:`~psi_io.psi_io.read_hdf_by_index` reads the HDF5 file and returns ``(data, r, t, p)`` — the scalar array followed by the three coordinate vectors. Index arguments control which portion of the grid is loaded: - ``None`` — load the full extent of that dimension. - An integer ``i`` — fix that dimension to the ``i``-th grid point (1-based), collapsing it to a length-1 array. Here the colatitude is fixed at index 71 (the equatorial plane, :math:`\theta_{71} \approx \pi/2`), while :math:`r` and :math:`\phi` span their full extents. The result is a 2-D surface in the equatorial plane colored by :math:`B_r`. .. GENERATED FROM PYTHON SOURCE LINES 55-65 .. code-block:: Python data, r, t, p = read_hdf_by_index(br_file, None, 71, None) plotter = Plot3d() plotter.show_axes() plotter.add_sun() plotter.add_2d_slice(r, t, p, data, cmap='seismic', clim=(-1, 1), show_scalar_bar=True) plotter.show() .. tab-set:: .. tab-item:: Static Scene .. image-sg:: /gallery/01_getting_started/images/sphx_glr_p03_loading_data_001.png :alt: p03 loading data :srcset: /gallery/01_getting_started/images/sphx_glr_p03_loading_data_001.png :class: sphx-glr-single-img .. tab-item:: Interactive Scene .. offlineviewer:: /Users/rdavidson/MHDweb/pyvisual/docs/source/gallery/01_getting_started/images/sphx_glr_p03_loading_data_001.vtksz .. GENERATED FROM PYTHON SOURCE LINES 66-74 Scaling by :math:`r^2` ----------------------- The radial magnetic field falls off geometrically as :math:`1/r^2` with distance. Multiplying by :math:`r^2` removes this trend and reveals the longitudinal structure of open-field regions at all radii — a common diagnostic in solar wind modeling. Because ``r`` is a plain NumPy array, the scaling is a single element-wise operation before passing to the plotter. .. GENERATED FROM PYTHON SOURCE LINES 74-80 .. code-block:: Python plotter = Plot3d() plotter.show_axes() plotter.add_sun() plotter.add_2d_slice(r, t, p, data * r ** 2, cmap='seismic', clim=(-1, 1), show_scalar_bar=True) plotter.show() .. tab-set:: .. tab-item:: Static Scene .. image-sg:: /gallery/01_getting_started/images/sphx_glr_p03_loading_data_002.png :alt: p03 loading data :srcset: /gallery/01_getting_started/images/sphx_glr_p03_loading_data_002.png :class: sphx-glr-single-img .. tab-item:: Interactive Scene .. offlineviewer:: /Users/rdavidson/MHDweb/pyvisual/docs/source/gallery/01_getting_started/images/sphx_glr_p03_loading_data_002.vtksz .. rst-class:: sphx-glr-timing **Total running time of the script:** (0 minutes 1.603 seconds) .. _sphx_glr_download_gallery_01_getting_started_p03_loading_data.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: p03_loading_data.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: p03_loading_data.py ` .. container:: sphx-glr-download sphx-glr-download-zip :download:`Download zipped: p03_loading_data.zip ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_