Change coordinates for origin in scatter plot with centred axes

Question

I have some datasets that I'm visualizing in a scatter plot. I have a bunch of mean values, and a global mean. What I'm after, but cant really achieve,is to have a scatter plot that is centered in the plot, while also placing the origin at the global mean.

This is the code that defines the layout of the plot:

plt.figure(1)
plt.suptitle('Example')
plt.xlabel('x (pixels)')
plt.ylabel('y (pixels)')
ax = plt.gca()
ax.spines['left'].set_position('center')
ax.spines['right'].set_color('none')
ax.spines['bottom'].set_position('center')
ax.spines['top'].set_color('none')
ax.scatter(x_data, y_data, color=color, alpha=0.08, label=csv_file_name)
ax.plot(global_mean[0], global_mean[1], color='green',
            marker='x', label='Global mean')

This produces the following plot (the ax.scatter() is called multiple times for each dataset, but it's not in the code above):

I've tried playing around with the ax.set_position() parameters but nothing have worked well so far. Is there a way to do what I'm after with matplotlib, or do I need to use some other plot library?

Answer 1

You can use the ax.spines() method to move them around.

import numpy as np
import random
import matplotlib.pyplot as plt

#generate some random data
x = np.linspace(1,2, 100)
y = [random.random() for _ in range(100)]

fig = plt.figure(figsize=(10,5))

# original plot
ax = fig.add_subplot(1,2,1)
ax.scatter(x, y)

# same plot, but with the spines moved
ax2 = fig.add_subplot(1,2,2)
ax2.scatter(x, y)
# move the left spine (y axis) to the right
ax2.spines['left'].set_position(('axes', 0.5))
# move the bottom spine (x axis) up
ax2.spines['bottom'].set_position(('axes', 0.5))
# turn off the right and top spines
ax2.spines['right'].set_visible(False)
ax2.spines['top'].set_visible(False)

plt.show()