set_ticks_position to non-default position, sets all tick texts to empty string

[olgabot]

When setting yticklabels or xticklabels and then setting the position, the tick._text field gets cleared.

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.plot([0, 1], [0, 1])

ax.set_yticklabels(list('asdfgh'))

print('before')
print('ax.get_yticklabels', map(lambda x: x._text, ax.get_yticklabels()))

ax.yaxis.set_ticks_position('right')

print('\nafter')
print('ax.get_yticklabels', map(lambda x: x._text, ax.get_yticklabels()))
print('ax.get_ymajorticklabels', map(lambda x: x._text, ax.get_ymajorticklabels()))
print('ax.get_yminorticklabels', map(lambda x: x._text, ax.get_yminorticklabels()))

results in

before
('ax.get_yticklabels', [u'a', u's', u'd', u'f', u'g', u'h'])

after
('ax.get_yticklabels', [u'', u'', u'', u'', u'', u''])
('ax.get_ymajorticklabels', [u'', u'', u'', u'', u'', u''])
('ax.get_yminorticklabels', [])

This is true for either x- or y-ticklabels

However, the behavior is as expected when the position is set first, then the ticklabel values are set:

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.plot([0, 1], [0, 1])

ax.yaxis.set_ticks_position('right')


print('before')
print('ax.get_yticklabels', map(lambda x: x._text, ax.get_yticklabels()))

ax.set_yticklabels(list('asdfgh'))

print('\nafter')
print('ax.get_yticklabels', map(lambda x: x._text, ax.get_yticklabels()))
print('ax.get_ymajorticklabels', map(lambda x: x._text, ax.get_ymajorticklabels()))
print('ax.get_yminorticklabels', map(lambda x: x._text, ax.get_yminorticklabels()))

results in:

before
('ax.get_yticklabels', [u'', u'', u'', u'', u'', u''])

after
('ax.get_yticklabels', [u'a', u's', u'd', u'f', u'g', u'h'])
('ax.get_ymajorticklabels', [u'a', u's', u'd', u'f', u'g', u'h'])
('ax.get_yminorticklabels', [])

Full example, plus pip list:
http://nbviewer.ipython.org/gist/anonymous/11332415

Any ideas what may be going on? From delving into the code, I'm taking a wild guess that it's something in Tick._apply_params that may be going awry, but really not sure.

[tacaswell]

I strongly suspect that this is the same issue as #2941 which results from a cla an the axis object when you move the axis location.

[efiring]

It's not a bug, it's a feature...
The axis actually keeps two sets of ticks and labels, one for each side. When you call set_ticks_position('right') you are just telling the axis to hide the left-hand ticks and show the right-hand ticks. Since your call to set_yticklabels() was made when the left-hand side was active, it set only the left-hand labels. In fact, if at the end of your example you call `set_ticks_position('left') and print, you will see that the labels are still there.
It's a bit confusing. I suspect that if we were starting from scratch we could now design a simpler and more transparent API; but given where we are, I don't see any obvious change to make related to this issue.

[efiring]

#2941 is different; it is addressed by #3104.