Interval dtype fix

pandas/core/dtypes/dtypes.py

@@ -931,10 +931,15 @@ def construct_from_string(cls, string):
  attempt to construct this type from a string, raise a TypeError
  if its not possible
  """
- if (isinstance(string, compat.string_types) and
- (string.startswith('interval') or
- string.startswith('Interval'))):
- return cls(string)
+ if isinstance(string, compat.string_types):
+ if (string.lower() == 'interval' or
+ cls._match.search(string) is not None):
+ return cls(string)
+ else:
+ msg = ('Incorrectly formatted string passed to constructor. '
+ 'Valid formats include Interval or Inverval[dtype] '
+ 'where dtype is numeric, datetime, or timedelta')
+ raise TypeError(msg)
 
  msg = "a string needs to be passed, got type {typ}"
  raise TypeError(msg.format(typ=type(string)))
@@ -978,7 +983,7 @@ def is_dtype(cls, dtype):
  return True
  else:
  return False
- except ValueError:
+ except (ValueError, TypeError):
  return False
  else:
  return False

pandas/tests/dtypes/test_dtypes.py

@@ -511,10 +511,11 @@ def test_construction_not_supported(self, subtype):
  with pytest.raises(TypeError, match=msg):
  IntervalDtype(subtype)
 
- def test_construction_errors(self):
+ @pytest.mark.parametrize('subtype', ['xx', 'IntervalA', 'Interval[foo]'])
+ def test_construction_errors(self, subtype):
  msg = 'could not construct IntervalDtype'
  with pytest.raises(TypeError, match=msg):
- IntervalDtype('xx')
+ IntervalDtype(subtype)
 
  def test_construction_from_string(self):
  result = IntervalDtype('interval[int64]')
@@ -523,7 +524,7 @@ def test_construction_from_string(self):
  assert is_dtype_equal(self.dtype, result)
 
  @pytest.mark.parametrize('string', [
- 'foo', 'foo[int64]', 0, 3.14, ('a', 'b'), None])
+ 0, 3.14, ('a', 'b'), None])
  def test_construction_from_string_errors(self, string):
  # these are invalid entirely
  msg = 'a string needs to be passed, got type'
@@ -532,13 +533,16 @@ def test_construction_from_string_errors(self, string):
  IntervalDtype.construct_from_string(string)
 
  @pytest.mark.parametrize('string', [
- 'interval[foo]'])
+ 'foo', 'foo[int64]'])
  def test_construction_from_string_error_subtype(self, string):
  # this is an invalid subtype
- msg = 'could not construct IntervalDtype'
+ msg = ('Incorrectly formatted string passed to constructor. '
+ 'Valid formats include Interval or Inverval[dtype] '
+ 'where dtype is numeric, datetime, or timedelta')
 
- with pytest.raises(TypeError, match=msg):
+ with pytest.raises(TypeError) as e:
  IntervalDtype.construct_from_string(string)
+ assert e == msg
 
  def test_subclass(self):
  a = IntervalDtype('interval[int64]')
@@ -559,6 +563,7 @@ def test_is_dtype(self):
  assert not IntervalDtype.is_dtype('U')
  assert not IntervalDtype.is_dtype('S')
  assert not IntervalDtype.is_dtype('foo')
+ assert not IntervalDtype.is_dtype('IntervalA')
  assert not IntervalDtype.is_dtype(np.object_)
  assert not IntervalDtype.is_dtype(np.int64)
  assert not IntervalDtype.is_dtype(np.float64)