Merge pull request #402 from data-8/warn_with_columns

Adds exception for Table.with_columns(...)

CHANGELOG.md

@@ -4,6 +4,9 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+### v0.13.6
+* Adds a warning to help students realize why `Table.with_columns(...)` doesn't work.
+
 ### v0.13.5
 * Adds support for other built-in tile sets other than `OpenStreetMap` to `Map`.
 

datascience/tables.py

@@ -1734,6 +1734,9 @@ def with_columns(self, *labels_and_values, **formatter):
             ...
         ValueError: Column length mismatch. New column does not have the same number of rows as table.
         """
+        if not isinstance(self, Table):
+            raise TypeError('Use Table().with_columns() to create a new table, \
+                not Table.with_columns()')
         if len(labels_and_values) == 1:
             labels_and_values = labels_and_values[0]
         if isinstance(labels_and_values, collections.abc.Mapping):

datascience/version.py

@@ -1 +1 @@
-__version__ = '0.13.5'
+__version__ = '0.13.6'

tests/test_tables.py

@@ -859,6 +859,10 @@ def test_with_columns():
     110235    | 0.236 | $15,500,000 | 2016   | 1
     """)
 
+def test_with_columns_exception_for_incorrect_usage():
+    with(pytest.raises(TypeError)):
+        Table.with_columns('player_id', make_array(110234, 110235), 'wOBA', make_array(.354, .236))
+
 def test_with_columns_with_formats():
     players = Table().with_columns('player_id', make_array(110234, 110235), 'wOBA', make_array(.354, .236))
     assert_equal(players, """