CODEWITHSUNDEEP
pythonmatplotlibseabornheatmap
Marcelo
Marcelo

Reputation: 77

How to add customized ticks in Heatmap?

I plotted an array in seaborn heatmap, and I want to add tick limits to the axis.

My code:

# plot
eixoz = numpy.linspace(0, Z)
eixor = numpy.linspace(ra, R, nr)
eixox = D
numpy.meshgrid(eixoz, eixor)
ax = seaborn.heatmap(eixox)
ax.invert_yaxis()
plt.xlabel("Eixo z",  fontsize=20)
plt.ylabel("Eixo r", fontsize=20)
ax.get_xaxis().set_ticks([])
ax.get_yaxis().set_ticks([])
ax.collections[0].colorbar.set_label("Celsius", fontsize=20)
plt.show()

How can I add those limit ticks in blue? And also, how can I resize the color bar numbers?

enter image description here

Upvotes: 1

Views: 167

Answers (1)

JohanC
JohanC

Reputation: 80329

The size of the colorbar tick labels can be changed via ax.collections[0].colorbar.ax.tick_params(labelsize=20).

Text at the start and end of the axes can be place using the axes transform, where 0 is the left (or bottom) and 1 is the right (or top) of the axes. Negative values (or values larger than 1) are proportionall outside the axes area. Horizontal and vertical lines can use the same transform, but unlike text need clip_on=False to be drawn outside the axes area.

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

sns.set()
len_eixoz = 20
eixox = np.repeat(np.arange(37.55, 37.66, 0.02), len_eixoz).reshape(-1, len_eixoz)
ax = sns.heatmap(eixox)
ax.invert_yaxis()
ax.set_xlabel("Eixo z", fontsize=20)
ax.set_ylabel("Eixo r", fontsize=20)
ax.get_xaxis().set_ticks([])
ax.get_yaxis().set_ticks([])
ax.collections[0].colorbar.set_label("Celsius", fontsize=20)
cbar = ax.collections[0].colorbar.ax.tick_params(labelsize=20)

x0, x1 = 1, 2
y0, y1 = 0, 1
ax.text(0, -0.07, x0, ha='center', va='top', fontsize=20, color='steelblue', transform=ax.transAxes)
ax.text(1, -0.07, x1, ha='center', va='top', fontsize=20, color='steelblue', transform=ax.transAxes)
ax.text(-0.05, 0, y0, ha='right', va='center', fontsize=20, color='steelblue', transform=ax.transAxes)
ax.text(-0.05, 1, y1, ha='right', va='center', fontsize=20, color='steelblue', transform=ax.transAxes)

ax.vlines([0, 1], [0, 0], [-0.06, -0.06], color='crimson', clip_on=False, transform=ax.transAxes)
ax.hlines([0, 1], [0, 0], [-0.04, -0.04], color='crimson', clip_on=False, transform=ax.transAxes)
plt.tight_layout()
plt.show()

example plot

Note that calling sns.set(font_scale=1.8) at the start would scale all fonts.

Upvotes: 1

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