Vertical line not respecting min,max limits (matplotlib)

Question

Minimal working example of the issue:

import matplotlib.pyplot as plt

horiz_line = 0.0005
vert_line = 110
x_data = [10, 30, 50, 70, 90, 110, 130, 150, 170, 190, 210, 230, 250, 270, 290, 310, 330, 350, 370, 390, 410, 430, 450, 470, 490]
y_data = [0.0074999999999999997, 0.011875, 0.0057812499999999999, 0.0036458333333333334, 0.0020312500000000001, 0.0013125000000000001, 0.00098958333333333342, 0.00089285714285714283, 0.00074218750000000001, 0.00093749999999999997, 0.00071874999999999999, 0.00088068181818181821, 0.00078125000000000004, 0.0004807692307692308, 0.00055803571428571425, 0.00083333333333333339, 0.00066406250000000005, 0.00069852941176470592, 0.00059027777777777778, 0.00059210526315789478, 0.00062500000000000001, 0.0007291666666666667, 0.00068181818181818187, 0.00059782608695652171, 0.00053385416666666663]

fig = plt.figure() # create the top-level container

# horizontal line
plt.axhline(y=horiz_line, xmin=0, xmax=max(x_data), color='red', zorder=1)

# vertical line
plt.axvline(x=vert_line, ymin=0, ymax=max(y_data), color='red', zorder=2)

plt.scatter(x_data, y_data, s=150, color='blue', zorder=3)

plt.show()

Which gives me this:

Notice the little red vertical line at x=110. Why is it not respecting the min & max limits I set with ymin=0, ymax=max(y_data) (which should be min=0 ; max=0.011875)?

Answer 1

It seems you want the functionality provided by hlines and vlines rather than axhline and axvline, as the two latter uses the Axes coordinate system, while hlines and vlines use the data coordinate system.

So your code should be

import matplotlib.pyplot as plt

horiz_line = 0.0005
vert_line = 110
x_data = [10, 30, 50, 70, 90, 110, 130, 150, 170, 190, 210, 230, 250, 270, 290, 310, 330, 350, 370, 390, 410, 430, 450, 470, 490]
y_data = [0.0074999999999999997, 0.011875, 0.0057812499999999999, 0.0036458333333333334, 0.0020312500000000001, 0.0013125000000000001, 0.00098958333333333342, 0.00089285714285714283, 0.00074218750000000001, 0.00093749999999999997, 0.00071874999999999999, 0.00088068181818181821, 0.00078125000000000004, 0.0004807692307692308, 0.00055803571428571425, 0.00083333333333333339, 0.00066406250000000005, 0.00069852941176470592, 0.00059027777777777778, 0.00059210526315789478, 0.00062500000000000001, 0.0007291666666666667, 0.00068181818181818187, 0.00059782608695652171, 0.00053385416666666663]

fig = plt.figure() # create the top-level container

# horizontal line
plt.hlines(y=horiz_line, xmin=0, xmax=max(x_data), color='red', zorder=1)

# vertical line
plt.vlines(x=vert_line, ymin=0, ymax=max(y_data), color='red', zorder=2)

plt.scatter(x_data, y_data, s=150, color='blue', zorder=3)

plt.show()