Dear developers,
the following example shows a somewhat unexpected behaviour of the
get_xlim() method of an axis object: it returns a view to the internal
data structure used to store the data limits. Because of this saving and
restoring the data limits failed in this example (I am using matplotlib
0.98.3):
from pylab import *
plot([0,1], [0,1]) #create some plot
ax = gca() #keep reference to axis
#after some time, I want to change the plot content, but keep the data
limits
xlimits = ax.get_xlim() #save limits
print xlimits
ax.clear() #first clear axis, then
plot([1,2], [1,2]) #create new plot content
ax.set_xlim(xlimits) #does _not_ restore old limits
print xlimits #since saved xlimits also changed
Now I know that I have to use
xlimits = ax.get_xlim().copy()
if I want to save the data limits.
Is this really an intended behaviour? Wouldn't it be better if
get_xlim() already returns a copy? Or could at least the documentation
be updated to mention this pitfall?
Gregor
|
