[FIX] Fix guessing strategy for date and time variables

Orange/data/io.py

@@ -145,30 +145,39 @@ def guess_data_type(orig_values, namask=None):
     """
     valuemap, values = None, orig_values
     is_discrete = is_discrete_values(orig_values)
+    orig_values = np.asarray(orig_values, dtype=str)
+    if namask is None:
+        namask = isnastr(orig_values)
     if is_discrete:
         valuemap = sorted(is_discrete)
         coltype = DiscreteVariable
     else:
         # try to parse as float
-        orig_values = np.asarray(orig_values)
-        if namask is None:
-            namask = isnastr(orig_values)
         values = np.empty_like(orig_values, dtype=float)
         values[namask] = np.nan
         try:
             np.copyto(values, orig_values, where=~namask, casting="unsafe")
         except ValueError:
-            tvar = TimeVariable('_')
-            try:
-                values[~namask] = [tvar.parse(i) for i in orig_values[~namask]]
-            except ValueError:
-                coltype = StringVariable
-                # return original_values
-                values = orig_values
-            else:
-                coltype = TimeVariable
+            values = orig_values
+            coltype = StringVariable
         else:
             coltype = ContinuousVariable
+
+    if coltype is not ContinuousVariable:
+        # when not continuous variable it can still be time variable even it
+        # was before recognized as a discrete
+        tvar = TimeVariable('_')
+        # introducing new variable prevent overwriting orig_values and values
+        temp_values = np.empty_like(orig_values, dtype=float)
+        try:
+            temp_values[~namask] = [
+                tvar.parse_exact_iso(i) for i in orig_values[~namask]]
+        except ValueError:
+            pass
+        else:
+            valuemap = None
+            coltype = TimeVariable
+            values = temp_values
     return valuemap, values, coltype
 
 

Orange/data/tests/test_io.py

@@ -1,7 +1,8 @@
 import unittest
 import numpy as np
 
-from Orange.data import ContinuousVariable, DiscreteVariable, StringVariable
+from Orange.data import ContinuousVariable, DiscreteVariable, StringVariable, \
+    TimeVariable
 from Orange.data.io import guess_data_type
 
 
@@ -68,3 +69,27 @@ def test_guess_data_type_string(self):
         self.assertEqual(StringVariable, coltype)
         self.assertIsNone(valuemap)
         np.testing.assert_array_equal(in_values, values)
+
+    def test_guess_data_type_time(self):
+        in_values = ["2019-10-10", "2019-10-10", "2019-10-10", "2019-10-01"]
+        valuemap, _, coltype = guess_data_type(in_values)
+        self.assertEqual(TimeVariable, coltype)
+        self.assertIsNone(valuemap)
+
+        in_values = ["2019-10-10T12:08:51", "2019-10-10T12:08:51",
+                     "2019-10-10T12:08:51", "2019-10-01T12:08:51"]
+        valuemap, _, coltype = guess_data_type(in_values)
+        self.assertEqual(TimeVariable, coltype)
+        self.assertIsNone(valuemap)
+
+        in_values = ["2019-10-10 12:08:51", "2019-10-10 12:08:51",
+                     "2019-10-10 12:08:51", "2019-10-01 12:08:51"]
+        valuemap, _, coltype = guess_data_type(in_values)
+        self.assertEqual(TimeVariable, coltype)
+        self.assertIsNone(valuemap)
+
+        in_values = ["2019-10-10 12:08", "2019-10-10 12:08",
+                     "2019-10-10 12:08", "2019-10-01 12:08"]
+        valuemap, _, coltype = guess_data_type(in_values)
+        self.assertEqual(TimeVariable, coltype)
+        self.assertIsNone(valuemap)

Orange/data/variable.py

@@ -889,6 +889,13 @@ class TimeVariable(ContinuousVariable):
              r'\d{2}\d{2}\d{2}\.\d+|'
              r'\d{1,4}(-?\d{2,3})?'
              r')$')
+
+    class InvalidDateTimeFormatError(ValueError):
+        def __init__(self, date_string):
+            super().__init__(
+                "Invalid datetime format '{}'. "
+                "Only ISO 8601 supported.".format(date_string))
+
     _matches_iso_format = re.compile(REGEX).match
 
     # UTC offset and associated timezone. If parsed datetime values provide an
@@ -954,16 +961,14 @@ def parse(self, datestr):
             return Unknown
         datestr = datestr.strip().rstrip('Z')
 
-        ERROR = ValueError("Invalid datetime format '{}'. "
-                           "Only ISO 8601 supported.".format(datestr))
         if not self._matches_iso_format(datestr):
             try:
                 # If it is a number, assume it is a unix timestamp
                 value = float(datestr)
                 self.have_date = self.have_time = 1
                 return value
             except ValueError:
-                raise ERROR
+                raise self.InvalidDateTimeFormatError(datestr)
 
         for i, (have_date, have_time, fmt) in enumerate(self._ISO_FORMATS):
             try:
@@ -984,7 +989,7 @@ def parse(self, datestr):
                                     self.UNIX_EPOCH.day)
                 break
         else:
-            raise ERROR
+            raise self.InvalidDateTimeFormatError(datestr)
 
         # Remember UTC offset. If not all parsed values share the same offset,
         # remember none of it.
@@ -1010,6 +1015,16 @@ def parse(self, datestr):
         except OverflowError:
             return -(self.UNIX_EPOCH - dt).total_seconds()
 
+    def parse_exact_iso(self, datestr):
+        """
+        This function is a meta function to `parse` function. It checks
+        whether the date is of the iso format - it does not accept float-like
+        date.
+        """
+        if not self._matches_iso_format(datestr):
+            raise self.InvalidDateTimeFormatError(datestr)
+        return self.parse(datestr)
+
     def to_val(self, s):
         """
         Convert a value, given as an instance of an arbitrary type, to a float.