How to plot subplots horizontally and vertically aligned with respect to each other in matplotlib? - matplotlib

Question

I have 3 subplots in matplotlib (2 rows and 3 columns).
I intend to have the first subplot in the 1st row covering the all 3 columns;
second subplot in the 2nd row left most aligned
third subplot in the 2nd row right most aligned.
Both second and third subplots horizontally aligned to the top with respect to each other.
However with the code below, I could not horizontally align them.
I also used gridspec.GridSpec with some width_ratios.
import numpy as np
import os
import matplotlib.pyplot as plt
from matplotlib.lines import Line2D
from matplotlib import gridspec
def plot_figure():
xticklabels_list = ['a','b','c','d','e','f'] * 6
rows=['row1']
plot1 = plt.figure(figsize=(5 + 1.5 * len(xticklabels_list), 5 + 1.5 * len(rows)))
gs = gridspec.GridSpec(2, 3, width_ratios=[1, 1, 1], height_ratios=[1, 1])
top_axis = plt.subplot(gs[0, :])
bottom_left_axis = plt.subplot(gs[-1, 0])
bottom_right_axis = plt.subplot(gs[-1, -1])
plot_at_bottom_left_axis(bottom_left_axis)
top_axis.set_xlim([0, 36])
top_axis.set_xticklabels([])
top_axis.tick_params(axis='x', which='minor', length=0, labelsize=35)
top_axis.set_xticks(np.arange(0, 36, 1))
top_axis.set_xticks(np.arange(0, 36, 1) + 0.5, minor=True)
top_axis.set_xticklabels(xticklabels_list, minor=True)
top_axis.xaxis.set_label_position('top')
top_axis.xaxis.set_ticks_position('top')
plt.tick_params(
axis='x', # changes apply to the x-axis
which='major', # both major and minor ticks are affected
bottom=False, # ticks along the bottom edge are off
top=False) # labels along the bottom edge are off
# CODE GOES HERE TO CENTER Y-AXIS LABELS...
top_axis.set_ylim([0, len(rows)])
top_axis.set_yticklabels([])
top_axis.tick_params(axis='y', which='minor', length=0, labelsize=40)
top_axis.set_yticks(np.arange(0, len(rows), 1))
top_axis.set_yticks(np.arange(0, len(rows), 1) + 0.5, minor=True)
top_axis.set_yticklabels(rows, minor=True) # fontsize
plt.tick_params(
axis='y', # changes apply to the x-axis
which='major', # both major and minor ticks are affected
left=False) # labels along the bottom edge are off
# Gridlines based on major ticks
top_axis.grid(which='major', color='black', zorder=3)
# Put the legend
legend_elements = [ Line2D([0], [0], marker='o', color='white', label='legend1', markerfacecolor='red',markersize=40),
Line2D([0], [0], marker='o', color='white', label='legend2', markerfacecolor='green',markersize=40)]
bottom_right_axis.set_axis_off()
bottom_right_axis.legend(handles=legend_elements, ncol=len(legend_elements), bbox_to_anchor=(1,1), loc='upper right',fontsize=40)
figFile = os.path.join('/Users/burcakotlu/Desktop', 'test.png')
plot1.savefig(figFile, dpi=100, bbox_inches="tight")
plt.cla()
plt.close(plot1)
def plot_at_bottom_left_axis(ax):
box = ax.get_position()
ax.set_position([0, 1, box.width * 1, box.height * 1], which='active')
diameter_labels = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]
diameter_ticklabels = ['label1', '', '', '', 'label2', '', '', '', '', 'label3']
row_labels = ['circle']
ax.grid(which="major", color="w", linestyle='-', linewidth=3)
plt.setp(ax.spines.values(), color='white')
ax.set_aspect(1.0)
ax.set_facecolor('lightcyan')
# CODE GOES HERE TO CENTER X-AXIS LABELS...
ax.set_xlim([0, len(diameter_labels)])
ax.set_xticklabels([])
ax.tick_params(axis='x', which='both', length=0, labelsize=30)
ax.set_xticks(np.arange(0, len(diameter_labels), 1))
ax.set_xticks(np.arange(0, len(diameter_labels), 1) + 0.5, minor=True)
ax.set_xticklabels(diameter_ticklabels, minor=True)
ax.xaxis.set_ticks_position('bottom')
plt.tick_params(
axis='x', # changes apply to the x-axis
which='both', # both major and minor ticks are affected
bottom=False, # ticks along the bottom edge are off
top=False) # labels along the bottom edge are off
ax.set_xlabel('labels to be shown', fontsize=40, labelpad=10)
ax.set_ylim([0, len(row_labels)])
ax.set_yticklabels([])
ax.tick_params(axis='y', which='minor', length=0, labelsize=12)
ax.set_yticks(np.arange(0, len(row_labels), 1))
ax.set_yticks(np.arange(0, len(row_labels), 1) + 0.5, minor=True)
plt.tick_params(
axis='y', # changes apply to the x-axis
which='major', # both major and minor ticks are affected
left=False) # labels along the bottom edge are off
plot_figure()
Here is the resulting figure for the code above.