UninstantiatedColumn now passes unit tests

- Avoid creating many separate DataMatrix objects when selecting

datamatrix/_datamatrix/_basecolumn.py

@@ -584,7 +584,7 @@ def _getdatamatrixkey(self, key):
             raise ValueError('Cannot slice column with a different DataMatrix')
         return self[[self._rowid.index(_rowid) for _rowid in key._rowid]]
 
-    def _getrowidkey(self, key):
+    def _getrowidkey(self, key, dm=None):
 
         """
         visible: False
@@ -599,7 +599,7 @@ def _getrowidkey(self, key):
             BaseColunn
         """
         seq = [self._seq[self._rowid.index(_rowid)] for _rowid in key]
-        return self._empty_col(rowid=key, seq=seq)
+        return self._empty_col(rowid=key, seq=seq, datamatrix=dm)
 
     def _sortedrowid(self):
 

datamatrix/_datamatrix/_datamatrix.py

@@ -153,6 +153,10 @@ def empty(self):
     @property
     def columns(self):
 
+        for name, col in self._cols.items():
+            if isinstance(col, UninstantiatedColumn):
+                col = col.instantiate()
+                self._cols[name] = col
         return self._to_list(self._cols.items(), key=lambda col: col[0])
 
     @property
@@ -310,12 +314,13 @@ def _selectrowid(self, _rowid):
             # By default we create new columns with a copy of the selected data 
             if not hasattr(self, '_instantiate_on_select') or \
                     self._instantiate_on_select:
-                dm._cols[name] = self._cols[name]._getrowidkey(_rowid)
+                dm._cols[name] = self._cols[name]._getrowidkey(_rowid, dm)
             # Except when _instatiate_on_select is set to False, in which case
             # we create an UninstantiatedColumn object which can be turned into
             # an actual column when it is requested in _getcolbyname()
             else:
-                dm._cols[name] = UninstantiatedColumn(self._cols[name], _rowid)
+                dm._cols[name] = UninstantiatedColumn(
+                    name, self._cols[name], _rowid, dm)
             dm._cols[name]._datamatrix = dm
         return dm
 

datamatrix/_datamatrix/_numericcolumn.py

@@ -224,7 +224,7 @@ def _getintkey(self, key):
 
         return self.dtype(self._seq[key])
 
-    def _getrowidkey(self, key):
+    def _getrowidkey(self, key, dm=None):
 
         if isinstance(key, Index):
             key = key._a
@@ -249,7 +249,8 @@ def _getrowidkey(self, key):
         else:
             selected_indices = selected_indices_cache[1]
         return self._empty_col(rowid=self._rowid[selected_indices],
-                               seq=self._seq[selected_indices])
+                               seq=self._seq[selected_indices],
+                               datamatrix=dm)
 
     def _setdatamatrixkey(self, key, val):
 

datamatrix/_datamatrix/_uninstantiatedcolumn.py

@@ -25,15 +25,21 @@ class UninstantiatedColumn:
     
     Parameters
     ----------
+    name: str
     parent_col: BaseColumn
     rowid: Index
+    dm: DataMatrix
     """
-    def __init__(self, parent_col, rowid):
+    def __init__(self, name, parent_col, rowid, dm):
         logger.debug(
-            f'creating uninstantiatedselection from {parent_col.name}')
+            f'creating uninstantiatedselection from {name}')
         self._parent_col = parent_col
         self._rowid = rowid
+        self._dm = dm
+        self._name = name
 
     def instantiate(self):
-        logger.debug(f'instantiating selection from {self._parent_col.name}')
-        return self._parent_col._getrowidkey(self._rowid)
+        logger.debug(f'instantiating selection from {self._name}')
+        if isinstance(self._parent_col, UninstantiatedColumn):
+            self._parent_col = self._parent_col.instantiate()
+        return self._parent_col._getrowidkey(self._rowid, self._dm)