fill_between_steps.py

def fill_between_steps(x, y1, y2=0, h_align='mid', ax=None, **kwargs):
    ''' Fills a hole in matplotlib: fill_between for step plots.

    Parameters :
    ------------

    x : array-like
        Array/vector of index values. These are assumed to be equally-spaced.
        If not, the result will probably look weird...
    y1 : array-like
        Array/vector of values to be filled under.
    y2 : array-Like
        Array/vector or bottom values for filled area. Default is 0.

    **kwargs will be passed to the matplotlib fill_between() function.

    '''
    # If no Axes opject given, grab the current one:
    if ax is None:
        ax = plt.gca()
    # First, duplicate the x values
    xx = x.repeat(2)[1:]
    # Now: the average x binwidth
    xstep = sp.repeat((x[1:] - x[:-1]), 2)
    xstep = sp.concatenate(([xstep[0]], xstep, [xstep[-1]]))
    # Now: add one step at end of row.
    xx = sp.append(xx, xx.max() + xstep[-1])

    # Make it possible to chenge step alignment.
    if h_align == 'mid':
        xx -= xstep / 2.
    elif h_align == 'right':
        xx -= xstep

    # Also, duplicate each y coordinate in both arrays
    y1 = y1.repeat(2)#[:-1]
    if type(y2) == sp.ndarray:
        y2 = y2.repeat(2)#[:-1]

    # now to the plotting part:
    ax.fill_between(xx, y1, y2=y2, **kwargs)

    return ax