def add(self, key, a):
"""
Add Axes *a*, with key *key*, to the stack, and return the stack.
If *a* is already on the stack, don't add it again, but
return *None*.
"""
# All the error checking may be unnecessary; but this method
# is called so seldom that the overhead is negligible.
if not isinstance(a, Axes):
raise ValueError("second argument, %s, is not an Axes" % a)
try:
hash(key)
except TypeError:
raise ValueError("first argument, %s, is not a valid key" % key)
a_existing = self.get(key)
if a_existing is not None:
Stack.remove(self, (key, a_existing))
import warnings
warnings.warn(
"key %s already existed; Axes is being replaced" % key)
# I don't think the above should ever happen.
if a in self:
return None
self._ind += 1
return Stack.push(self, (key, (self._ind, a)))
def remove(self, a):
"""Remove the axes from the stack."""
Stack.remove(self, self._entry_from_axes(a))
