PlotEigValDistr
'''''''''''''''

.. function:: PlotEigValDistr(NumEigenvalues, FNmPref, DescStr)

A graph method for undirected graphs that plots the frequency distribution of the leading *NumEigenvalues* eigenvalues. The function creates three new files: 1) eigDistr.<*FNmPref*>.plt (the commands used to create the plot), 2) eigDistr.<*FNPref*>.png (the plot), and 3) eigDistr.<*FNmPref*>.tab (the plotting data).

Parameters:

- *NumEigenvalues*: int
    The plot will contain the frequencies of the first *NumEigenvalues* eigenvalues.

- *FNmPref*: string
    File name preference for the plotted graph.

- *DescStr*: string
    Description of the graph. The string should be non-empty.

Return value:

- None


The following example shows how to plot the eigenvalue frequency distribution of
an undirected graph of type :class:`TUNGraph`::

    import snap

    UGraph = snap.GenRndGnm(snap.TUNGraph, 100, 1000)

    # Plot the frequencies of the first 10 eigenvalues
    # NOTE: Random graphs are likely to thwart the calculation of eigenvalues
    UGraph.PlotEigValDistr(10, "example", "Random Graph Eigenvalue Distribution")