How I can get cartesian coordinate system in matplotlib?

Question

I am new to plotting with Python and can\'t really find an answer to the question: How can I get Cartesian coordinate plane in matplotlib? By this I mean perpendicular refe

Answer 1

Here is another way to draw a Cartesian coordinate system, built on the answers already given by others.

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots(figsize=(10, 10))

# Enter x,y coordinates and colors of points
x = [0, 2, -3, -1.5]
y = [0, 3, 1, -2.5]
color = ['m', 'g', 'r', 'b']

# Select length of axes and the space between tick labels
xmin, xmax, ymin, ymax = -5, 5, -5, 5
ticks_frequency = 1

# Plot points
ax.scatter(x, y, c=color)

# Draw lines connecting points to axes
[ax.plot([dot_x, dot_x], [0, dot_y], c=c, ls='--', lw=1.5, alpha=0.5) for dot_x, dot_y, c in zip(x, y, color)] 
[ax.plot([0, dot_x], [dot_y, dot_y], c=c, ls='--', lw=1.5, alpha=0.5) for dot_x, dot_y, c in zip(x, y, color)]

# Set identical scales for both axes
ax.set(xlim=(xmin-1, xmax+1), ylim=(ymin-1, ymax+1), aspect='equal')

# Set bottom and left spines as x and y axes of coordinate system
ax.spines['bottom'].set_position('zero')
ax.spines['left'].set_position('zero')

# Remove top and right spines
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)

# Create 'x' and 'y' labels placed at the end of the axes
ax.set_xlabel('x', size=14, labelpad=15)
ax.set_ylabel('y', size=14, labelpad=15, rotation=0)
ax.xaxis.set_label_coords(1.03, 0.512)
ax.yaxis.set_label_coords(0.5, 1.02)

# Create custom tick labels
x_ticks = np.arange(xmin, xmax+1, ticks_frequency)
x_ticks_major = x_ticks[x_ticks != 0]
y_ticks = np.arange(ymin, ymax+1, ticks_frequency)
y_ticks_major = y_ticks[y_ticks != 0]
ax.set_xticks(x_ticks_major)
ax.set_yticks(y_ticks_major)
ax.set_xticks(np.arange(xmin,xmax+1), minor=True)
ax.set_yticks(np.arange(ymin,ymax+1), minor=True)

# Draw grid lines
ax.grid(which='major', color='grey', linewidth=1, linestyle='-', alpha=0.2)
ax.grid(which='minor', color='grey', linewidth=1, linestyle='-', alpha=0.2)

# Draw arrows
ax.plot((1), (0), linestyle="", marker=">", markersize=4, color="k",
        transform=ax.get_yaxis_transform(), clip_on=False)
ax.plot((0), (1), linestyle="", marker="^", markersize=4, color="k",
        transform=ax.get_xaxis_transform(), clip_on=False)

plt.show()

Notice that I have not added annotations displaying the coordinates of the points as in my experience this requires a lot more code to place them nicely and with minimal overlapping. To get annotations, it is probably easier to use an interactive graphing library such as Plotly.