plot_heat_line.py

def plot_heatline(ax, x, y, c, w):
    """Plot a colour-coded segmented line graph with a border.
    Args:
        ax - the current axis.
        x - x-axis values.
        y - y-axis values.
        c - the colours for the segments in the line graph defined by x, y.
        w - the line widths for the segments in the line graph defined by x, y.    
    """
    
    # Reformat the x, y data to define the segments needed by LineCollection.
    points = np.array([x, y]).T.reshape(-1, 1, 2) # Create Nx1x2 array
    segments = np.concatenate(
        [points[:-1], points[1:]]
        , axis=1
    ) # Pairs of (x,y) points for each segment.
    
    # Build the heat line; each segment with teh segment colors and widths.
    heat_line = LineCollection(segments, colors=c, linewidths=w)
    ax.add_collection(heat_line)