How to change the colorbar ticklabels to percent

Question

I have a problem with the colorbar of my kdeplot. It should show the percentage in each bin starting with 0%. I tried two different ways, but both visualizations are not exactly what I need.

The version with JointGrid starts indeed with 0%, but doesn't show the other values for each color. Furthermore I need the "background" to be white or at least bright (not black, but shaded).

The version with jointplot shows the values for each color, but not in percentage.

Here is the code I used to create the visualizations:

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns


x = np.random.normal(np.tile(np.random.uniform(-5, 35, 10), 1000), 4)
y = np.random.normal(np.tile(np.random.uniform(910, 1030, 10), 1000), 4)
data = pd.DataFrame(x,y)

g = sns.JointGrid(x, y, data=data, space=0, xlim=[10,40], ylim=[920,1020])
g = g.plot_joint(sns.kdeplot, cmap="Blues_d", shade=True, cbar=True, cbar_kws= 
{'format':'%.0f%%','ticks': [0, 100]})
g = g.plot_marginals(sns.kdeplot, shade=True)

plt.subplots_adjust(left=0.1, right=0.8, top=0.9, bottom=0.1)
pos_joint_ax = g.ax_joint.get_position()
pos_marg_x_ax = g.ax_marg_x.get_position()
g.ax_joint.set_position([pos_joint_ax.x0, pos_joint_ax.y0, pos_marg_x_ax.width, pos_joint_ax.height])
g.fig.axes[-1].set_position([.83, pos_joint_ax.y0, .07, pos_joint_ax.height])

plt.show()

kdeplot = sns.jointplot(x, y, kind="kde", cbar=True, xlim=[10,40], ylim=[920,1020])

plt.subplots_adjust(left=0.1, right=0.8, top=0.9, bottom=0.1)
pos_joint_ax = kdeplot.ax_joint.get_position()
pos_marg_x_ax = kdeplot.ax_marg_x.get_position()
kdeplot.ax_joint.set_position([pos_joint_ax.x0, pos_joint_ax.y0, pos_marg_x_ax.width, 
pos_joint_ax.height])
kdeplot.fig.axes[-1].set_position([.83, pos_joint_ax.y0, .07, pos_joint_ax.height])

plt.show()

Answer 1

To get the colors in reverse order (light for small values, dark for high values), change cmap="Blues_d" to cmap="Blues". (Note that sns.kdeplot also has an option shade_lowest= which can be set to False.)

The colorbar ticks seem to be fixed at the borders between each value. I couldn't find a way to replace the ticks, but changing their labels can be done. By dividing the tick value by their maximum and multiplying by 100% a percentage can be obtained. However, these are not at nice values for a scale from 0 to 100.

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

x = np.random.normal(np.tile(np.random.uniform(15, 35, 10), 1000), 4)
y = np.random.normal(np.tile(np.random.uniform(940, 1000, 10), 1000), 10)

kdeplot = sns.jointplot(x, y, kind="kde", cbar=True, xlim=[10, 40], ylim=[920, 1020])

plt.subplots_adjust(left=0.1, right=0.8, top=0.9, bottom=0.1)
pos_joint_ax = kdeplot.ax_joint.get_position()
pos_marg_x_ax = kdeplot.ax_marg_x.get_position()
kdeplot.ax_joint.set_position([pos_joint_ax.x0, pos_joint_ax.y0, pos_marg_x_ax.width,
                               pos_joint_ax.height])
kdeplot.fig.axes[-1].set_position([.83, pos_joint_ax.y0, .07, pos_joint_ax.height])

# get the current colorbar ticks
cbar_ticks = kdeplot.fig.axes[-1].get_yticks()
# get the maximum value of the colorbar
_, cbar_max = kdeplot.fig.axes[-1].get_ylim()
# change the labels (not the ticks themselves) to a percentage
kdeplot.fig.axes[-1].set_yticklabels([f'{t / cbar_max * 100:.1f} %' for t in cbar_ticks])

plt.show()