FIX: `to_table` failed on lists

Summary

Fix for #117 (closed)

Focus

• Performance
• Sufficient test

Test Environment

Run the unit test:

pytest --pdb --pdbcls=IPython.terminal.debugger:TerminalPdb unittests/test_table_converter.py::TableTest::test_list

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src/caosadvancedtools/table_converter.py

@@ -25,6 +25,7 @@ import re
 import sys
 
 import caosdb as db
+import numpy as np
 import pandas as pd
 
 
@@ -48,27 +49,25 @@ def generate_property_name(prop):
 
 
 def to_table(container):
-    """ creates a table from the records in a container """
+    """Create a table from the records in a container."""
 
     if len(container) == 0:
-        raise ValueError("Container is empty")
-    properties = set()
+        return pd.DataFrame()
+    rts = {p.name for p in container[0].parents}
 
+    data = []
     for rec in container:
-        properties.update([generate_property_name(p)
-                           for p in container[0].get_properties()])
-    df = pd.DataFrame(columns=list(properties))
-    rts = set([p.name for p in container[0].parents])
-
-    for ii, rec in enumerate(container):
-        if set([p.name for p in rec.parents]) != rts:
+        if {p.name for p in rec.parents} != rts:
             raise ValueError("Parents differ")
 
-        for p in rec.get_properties():
-
-            df.loc[ii, generate_property_name(p)] = p.value
+        row_dict = {}
+        for prop in rec.get_properties():
+            propname = generate_property_name(prop)
+            row_dict[propname] = prop.value
+        data.append(row_dict)
+    result = pd.DataFrame(data=data)
 
-    return df
+    return result
 
 
 def from_table(spreadsheet, recordtype):