def when(self, value, then) -> 'SwitchBuilder':
"""Add a value test. If the `base` expression is equal to `value`, then
returns `then`.
Warning
-------
Missingness always compares to missing. Both ``NA == NA`` and
``NA != NA`` return ``NA``. Use :meth:`~SwitchBuilder.when_missing`
to test missingness.
Parameters
----------
value : :class:`.Expression`
then : :class:`.Expression`
Returns
-------
:class:`.SwitchBuilder`
Mutates and returns `self`.
"""
can_compare = unify_types(self._base.dtype, value.dtype)
if not can_compare:
raise TypeError(
"cannot compare expressions of type '{}' and '{}'".format(
self._base.dtype, value.dtype))
self._unify_type(then.dtype)
self._cases.append((value, then))
return self
def when(self, value, then) -> 'SwitchBuilder':
"""Add a value test. If the `base` expression is equal to `value`, then
returns `then`.
Warning
-------
Missingness always compares to missing. Both ``NA == NA`` and
``NA != NA`` return ``NA``. Use :meth:`~SwitchBuilder.when_missing`
to test missingness.
Parameters
----------
value : :class:`.Expression`
then : :class:`.Expression`
Returns
-------
:class:`.SwitchBuilder`
Mutates and returns `self`.
"""
can_compare = unify_types(self._base.dtype, value.dtype)
if not can_compare:
raise TypeError("cannot compare expressions of type '{}' and '{}'".format(
self._base.dtype, value.dtype))
self._unify_type(then.dtype)
self._cases.append((self._base == value, then))
return self