How to change the positions of the objects

As you can see on the image below, my entire plot (whether it's the heatmaps, the title or the colorbar) is “tighten” in the top of the figure/window and there is a large blank space in the bottom

Is there a way to lower it entirely AND to reduce the blank space in the bottom?

I've already tried to use the fig.tight_layout() and to change the values of the figsize argument of the plt.figurefunction but the space in the bottom stays the same (proportionally)...

Here is the piece of code:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import AxesGrid
def graphs():
fig = plt.figure(figsize=(13.5, 6.8))
Grid = AxesGrid(fig, 111, nrows_ncols=(1,3), axes_pad=0.2, share_all=False, label_mode='L', cbar_location="bottom", cbar_mode="single")
Matrices = [np.random.randint(-100,10,(10,10)) for i in range(3)]
M, m = np.max(Matrices), np.min(Matrices)
for values, ax in zip(Matrices, Grid):
ax.tick_params(top = True, bottom = False, labeltop = True, labelbottom = False)
ax.xaxis.set_label_position('top')
heatmap = ax.imshow(values, vmin=m, vmax=M, cmap='plasma')
ax.set_xticks(np.arange(0,10), labels=list(np.arange(1,11)), fontsize=6)
ax.set_xlabel('Arrival', fontweight='bold', fontsize=8)
plt.setp(ax.get_xticklabels(), rotation=35, ha="center", rotation_mode=None)
for l in range(len(values)):
for c in range(len(values[l])):
text = ax.text(c, l, values[l,c], ha="center", va="center", color='k', fontsize=6)
ax.set_title('Gaps', fontweight='bold', fontsize=9)
Grid[0].set_yticks(np.arange(0,10), labels=list(np.arange(1,11)), fontsize=6)
Grid[0].set_ylabel('Depart', fontweight='bold', fontsize=8)
for cax in Grid.cbar_axes:
cax.remove()
cbar = Grid[0].figure.colorbar(heatmap, ax = Grid, fraction=0.2, aspect=50, location='bottom', label='Gaps')
plt.suptitle('Visualisation of different gaps', fontsize=15, fontweight='bold', y=0.97)
plt.show()

You don't trust Matplotlib capabilities.

To obtain the above figure, I have

1. left alone the contents of grille.cbar_axes
2. used grille.cbar_axes to place the colorbar
3. left the suptitle's position to be decided by Matplotlib
4. used plt.tight_layout() to have all the spaces left to a minimum

def graphs():
    fig = plt.figure(figsize=(13.5, 6.8), dpi=60) # low dpi to fit the window on my screen
    grille = AxesGrid(fig, 111, nrows_ncols=(1,3),
                      axes_pad=0.2, share_all=False, label_mode='L',
                      cbar_location="bottom", cbar_mode="single")

    Matrices = [np.random.randint(-100,10,(10,10)) for i in range(3)]
    M, m = np.max(Matrices), np.min(Matrices)

    for values, ax in zip(Matrices, grille):

        ax.tick_params(top = True, bottom = False, labeltop = True, labelbottom = False)
        ax.xaxis.set_label_position('top')

        heatmap = ax.imshow(values, vmin=m, vmax=M, cmap='plasma')
        ax.set_xticks(np.arange(0,10), labels=list(np.arange(1,11)), fontsize=6)/
        ax.set_xlabel('Arrival', fontweight='bold', fontsize=8)
        plt.setp(ax.get_xticklabels(), rotation=35, ha="center", rotation_mode=None)

        for l in range(len(values)):
            for c in range(len(values[l])):
                text = ax.text(c, l, values[l,c], ha="center", va="center", color='k', fontsize=6)

        ax.set_title('Gaps', fontweight='bold', fontsize=9)

    grille[0].set_yticks(np.arange(0,10), labels=list(np.arange(1,11)), fontsize=6)
    grille[0].set_ylabel('Depart', fontweight='bold', fontsize=8)

    cbar = plt.colorbar(heatmap, cax=grille.cbar_axes[0], orientation='horizontal', label='Gaps')
    plt.suptitle('Visualisation of different gaps', fontsize=15, fontweight='bold')
    plt.tight_layout()
    plt.show()
graphs()

Addendum

1. You can change the "thickness" and the spacing of the colorbar using appropriate keyword arguments to AxesGrid; e.g., in the following I've used cbar_size="2%", cbar_pad=0.05
   
2. Re white space, the whole of titles, plots and colorbar when packed has a well defined aspect ratio, additional white space is added vertically or horizontally according to the aspect ratio of the figure — here it is what happens when figsize=(13.5, 5)