cannot remove spines when using axes_grid1 after twin operation

[ocehugo]

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• [1.5.1,3.5.1,OSX ] Matplotlib version, Python version and Platform (Windows, OSX, Linux ...)
• [pip ] How did you install Matplotlib and Python (pip, anaconda, from source ...)

When creating a parasite object matplotlib creates two spines, and if one need to make it invisible by toggling one of them, the only time that it's possible is just after the creation of the parasite axis. If the user try to do it after calling new_fixed_axis the extra spine cannot be removed. For example the code below cannot remove the top extra spine.

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA
import numpy as np

host = host_subplot(111,axes_class=AA.Axes)
plt.subplots_adjust(bottom=0.15)
host.plot(10,10)
nfa = host.get_grid_helper().new_fixed_axis
par1 = host.twiny()
par1.axis['bottom'] = nfa(loc='bottom',axes=par1,offset=(0,-20))
par1.spine['top'].toggle(all=False)

While this works:

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA
import numpy as np

host = host_subplot(111,axes_class=AA.Axes)
plt.subplots_adjust(bottom=0.15)
host.plot(10,10)
nfa = host.get_grid_helper().new_fixed_axis
par1 = host.twiny()
par1.spine['top'].toggle(all=False)
par1.axis['bottom'] = nfa(loc='bottom',axes=par1,offset=(0,-20))

I would not expect that the toggle would work only just after creation of the parasite.

[tacaswell]

That is odd.

That part of the code base is under-tested and under-documented. Any help on it would be greatly appreciated.

[oscargus]

I think that the current version of this is:

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA

host = host_subplot(111,axes_class=AA.Axes)
plt.subplots_adjust(bottom=0.15)
host.plot(10,10)
nfa = host.get_grid_helper().new_fixed_axis
par1 = host.twiny()
par1.axis['bottom'] = nfa(loc='bottom',axes=par1,offset=(0,-20))
par1.spines['top'].set_visible(False)

Not fully sure what the expected outcome is, but swapping the two last lines will not change the plot (but I think that it is consistently incorrect now...).

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