Demonstrates bug in the tick-labels of a colorbar in axes_grid1 ImageGrid

axes_grid1_cbar_bug.py

import numpy as np
from matplotlib.pyplot import figure, scatter, colorbar
from matplotlib.colors import ListedColormap, BoundaryNorm

def get_colors():
    values = [0., 0.01, 0.1, 0.25, 0.5, 0.75, 1., 1.25, 1.5, 1.75, 2., 2.5, 3.,
             4., 5., 6., 7., 8., 9., 10., 11., 12., 13., 14., 15.]

    colors = ["#FFFFFF", "#7FFF00", "#00CD00", "#008B00", "#104E8B", "#1E90FF",
             "#00B2EE", "#00EEEE", "#8968CD", "#912CEE", "#8B008B", "#8B0000",
             "#CD0000", "#EE4000", "#FF7F00", "#CD8500", "#FFD700", "#EEEE00",
             "#FFFF00", "#7FFF00", "#00CD00", "#008B00", "#104E8B", "#1E90FF",
             "#00B2EE"]
    cmap = ListedColormap(colors[:-1])
    cmap.set_over(colors[-1])
    cmap.set_under(colors[0])
    normer = BoundaryNorm(values, cmap.N)
    return cmap, normer


def test_isolevels():
    cmap, normer = get_colors()
    x = y = c = np.arange(-1.0, 20, 1)
    art = scatter(x,y,c=c, s=50, cmap=cmap, norm=normer)
    cbar = colorbar(art)
    return art.figure


def axgrid_test():
    from mpl_toolkits.axes_grid1 import ImageGrid
    cmap, normer = get_colors()
    fig = figure()
    grid = ImageGrid(fig, 111, nrows_ncols = (1, 1), cbar_mode="each")
    ax = grid[0]
    x = y = c = np.arange(-1.0, 20, 1)
    art = ax.scatter(x,y,c=c, s=50, cmap=cmap, norm=normer)
    cbar = ax.cax.colorbar(art)
    return art.figure


if __name__ == '__main__':
    from pylab import show
    fig1 = test_isolevels()
    fig1.suptitle('Correct Colorbar Y-Tick Labels')
    fig2 = axgrid_test()
    fig2.suptitle('Incorrect Colorbar Y-Tick Labels')
    show()