python - matplotlib: Invert y axis on 3d bar graph

Question

I created 3d bar graph with matplotlib with the following code:

fig = plt.figure()
cmap = get_cmap(len(os.listdir(conv1d_kernel_path)))
ax = fig.add_subplot(111, projection='3d')

for f in os.listdir(conv1d_kernel_path):
    step = int(re.findall(r'd+', f)[0])
    conv1d_kernel_histo[f]['bins'] = convert_bins(30, min_weight, max_weight, conv1d_kernel_histo[f])

    bin_counts = conv1d_kernel_histo[f]['bins'][:, 2]
    width = (max_weight-min_weight)/30 #ToDo change 30 to numbins
    xs = conv1d_kernel_histo[f]['bins'][:, 0] + width / 2

    ax.bar(xs, list(bin_counts), width=width, zs=step, zdir='y', color=cmap(step), ec=cmap(step+20), alpha=0.8)

ax.set_xlabel('weights')
ax.set_ylabel('step')
ax.set_zlabel('count')

plt.show()

The directory and convert bins function isn't so important, just that it gives me the info I can use to define the input data that I iteratively pass to the ax.bar function. Anyways, I receive the following output:

I want to invert the axis titled 'steps', and this question seems to be nearly what I need; however, when I used ax.invert_yaxis() the axis titled 'weights' is inverted. When I alternatively use ax.invert_xaxis() the same axis is inverted. Out of curiosity, I tried ax.invert_zaxis() but that worked as one would think, and flipped the whole graph upside down. Does anybody have a solution to this problem? A different method for inverting the axis? Thanks, all help is appreciated

question from:https://stackoverflow.com/questions/65906056/matplotlib-invert-y-axis-on-3d-bar-graph

Answer 1

Well inverting the axis limits like ax.set_ylim(150,0) should work fine. Sample plot:

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
from matplotlib import cm
from matplotlib.ticker import LinearLocator, FormatStrFormatter
import numpy as np


fig = plt.figure()
ax = fig.gca(projection='3d')

# Make data.
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)
Z = np.sin(R)

# Plot the surface.
surf = ax.plot_surface(X, Y, Z, cmap=cm.coolwarm,
                       linewidth=0, antialiased=False)
# Invert Y-Axis
ax.set_ylim(4,-4)

# Customize the z axis.
ax.set_zlim(-1.01, 1.01)
ax.zaxis.set_major_locator(LinearLocator(10))
ax.zaxis.set_major_formatter(FormatStrFormatter('%.02f'))

# Add a color bar which maps values to colors.
fig.colorbar(surf, shrink=0.5, aspect=5)

plt.show()

Original:

Inverted Y-Axis: