Partial LuxSeries support for lux-org#66

Former-commit-id: a4d777d

lux/core/frame.py

@@ -1,4 +1,5 @@
 import pandas as pd
+from lux.core.series import LuxSeries
 from lux.vis.Clause import Clause
 from lux.vis.Vis import Vis
 from lux.vis.VisList import VisList
@@ -41,6 +42,18 @@ def __init__(self,*args, **kw):
 		self.cardinality = None
 		self.min_max = None
 		self.pre_aggregated = None
+
+	@property
+	def _constructor(self):
+		return LuxDataFrame
+
+	# @property
+	# def _constructor_sliced(self):
+	# 	def f(*args, **kwargs):
+	# 		# adapted from https://github.com/pandas-dev/pandas/issues/13208#issuecomment-326556232
+	# 		return LuxSeries(*args, **kwargs).__finalize__(self, method='inherit')
+	# 	return f
+
 	def maintain_metadata(self):
 		if (not hasattr(self,"_metadata_fresh") or not self._metadata_fresh ): # Check that metadata has not yet been computed
 			if (len(self)>0): #only compute metadata information if the dataframe is non-empty
@@ -558,6 +571,10 @@ def _repr_html_(self):
 				warnings.warn("\nLux can not operate on an empty dataframe.\nPlease check your input again.\n",stacklevel=2)
 				display(self.display_pandas()) 
 				return
+			if (len(self.columns)<=1):
+				warnings.warn("\nLux defaults to Pandas when there is only a single column.",stacklevel=2)
+				display(self.display_pandas()) 
+				return
 			self.maintain_metadata()
 
 			if (self._intent!=[] and not self._compiled):

lux/core/series.py

@@ -0,0 +1,19 @@
+import pandas as pd
+class LuxSeries(pd.Series):
+	# _metadata =  ['name','_intent','data_type_lookup','data_type',
+	# 			 'data_model_lookup','data_model','unique_values','cardinality',
+	# 			'min_max','plot_config', '_current_vis','_widget', '_recommendation']
+	def __init__(self,*args, **kw):
+		super(LuxSeries, self).__init__(*args, **kw)
+	@property
+	def _constructor(self):
+		return LuxSeries
+
+	@property
+	def _constructor_expanddim(self):
+		from lux.core.frame import LuxDataFrame
+		# def f(*args, **kwargs):
+		# 	# adapted from https://github.com/pandas-dev/pandas/issues/13208#issuecomment-326556232
+		# 	return LuxDataFrame(*args, **kwargs).__finalize__(self, method='inherit')
+		# return f
+		return LuxDataFrame

tests/test_pandas.py

@@ -0,0 +1,14 @@
+from .context import lux
+import pytest
+import pandas as pd
+
+# def test_df_to_series():
+#     # Ensure metadata is kept when going from df to series
+#     df = pd.read_csv("lux/data/car.csv")
+#     df._repr_html_() # compute metadata
+#     assert df.cardinality is not None
+#     series = df["Weight"]
+#     assert isinstance(series,lux.core.series.LuxSeries), "Derived series is type LuxSeries."
+#     assert df["Weight"]._metadata == ['name','_intent', 'data_type_lookup', 'data_type', 'data_model_lookup', 'data_model', 'unique_values', 'cardinality', 'min_max', 'plot_config', '_current_vis', '_widget', '_recommendation'], "Metadata is lost when going from Dataframe to Series."
+#     assert df.cardinality is not None, "Metadata is lost when going from Dataframe to Series."
+#     assert series.name == "Weight", "Pandas Series original `name` property not retained."