How to add colorbars to scatterplots created like this?

Question

I create scatterplots with code that, in essence, goes like this

cmap = (matplotlib.color.LinearSegmentedColormap.
        from_list(\'blueWhiteRed\', [\'blu         


        

Answer 1

I think this should do the trick. I'm pretty sure I grabbed this from one of the matplotlib cookbook examples a while back, but I can't seem to find it now...

from mpl_toolkits.axes_grid1 import make_axes_locatable

cmap = (matplotlib.color.LinearSegmentedColormap.
        from_list('blueWhiteRed', ['blue', 'white', 'red']))

fig = matplotlib.figure.Figure(figsize=(4, 4), dpi=72)
ax = fig.gca()

for record in data:
    level = record.level # a float in [0.0, 1.0]
    ax.scatter(record.x, record.y,
               c=level, vmin=0, vmax=1, cmap=cmap, **otherkwargs)

# various settings of ticks, labels, etc. omitted

divider= make_axes_locatable(ax)
cax = divider.append_axes("right", size="1%", pad=0.05)
cb = plt.colorbar(cax=cax)
cb.set_label('Cbar Label Here')

canvas = matplotlib.backends.backend_agg.FigureCanvasAgg(fig)
fig.set_canvas(canvas)
canvas.print_png('/path/to/output/fig.png')