.. include:: ../references.txt

.. _visualization_tutorial:

*************
Visualization
*************

Polycrystalline diffraction patterns may be hard to decrypt without some visualization tools. This tutorial goes over some of the tools available in `scikit-ued` that help solve this problem.

.. _patterson:

Patterson pair-pair distribution function
=========================================

The calculation of the Patterson pair-pair distribution requires knowledge of the investigated material. You must 
also determine what range of real-space radii over which you want to calculate the distribution. 

As an example, let's use a simulated diffraction pattern of monoclinic VO$_2$:

    >>> import numpy as np
    >>> import matplotlib.pyplot as plt
    >>> from crystals import Crystal
    >>> from skued import patterson, powdersim
    >>> 
    >>> # Simulation of polycrystalline diffraction pattern
    >>> # for monoclinic VO2
    >>> cryst = Crystal.from_database('vo2-m1')
    >>> q = np.linspace(0.2, 10, 1024)
    >>> I = powdersim(cryst, q)
    >>> 
    >>> # Determination of the pair-pair distribution function
    >>> rr = np.linspace(1, 5, 256)
    >>> pairdist = patterson(q = q, I = I, crystal = cryst, radii = rr)
    >>> 
    >>> fig, ax = plt.subplots(1,1)
    >>> ax.plot(rr, pairdist, '.k') # doctest: +SKIP
    
.. plot::

    import numpy as np
    import matplotlib.pyplot as plt
    from crystals import Crystal 
    from skued import patterson
    from skued import powdersim # To simulate experimental data
    
    # Simulation of polycrystalline diffraction pattern
    # for monoclinic VO2
    cryst = Crystal.from_database('vo2-m1')
    q = np.linspace(0.2, 10, 1024)
    I = powdersim(cryst, q)

    # Determination of the pair-pair distribution function
    rr = np.linspace(1, 5, 256)
    pairdist = patterson(q = q, I = I, crystal = cryst, radii = rr)

    fig, ax = plt.subplots(1,1)
    ax.plot(rr, pairdist, '.k')
    ax.set_xlabel('Radial distance $\AA$')
    ax.set_ylabel('Pair-pair correlation [a.u.]')
    
:ref:`Return to Top <visualization_tutorial>`