Daniel Shields created SPARK-24949:
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Summary: pyspark.sql.Column breaks the iterable contract
Key: SPARK-24949
URL: https://issues.apache.org/jira/browse/SPARK-24949
Project: Spark
Issue Type: Bug
Components: PySpark
Affects Versions: 2.3.1
Reporter: Daniel Shields
pyspark.sql.Column implements __iter__ just to raise a TypeError:
{code:java}
def __iter__(self):
raise TypeError("Column is not iterable")
{code}
This makes column look iterable even when it isn't:
{code:java}
isinstance(mycolumn, collections.Iterable) # Evaluates to True{code}
This function should be removed from Column completely so it behaves like every
other non-iterable class.
For further motivation of why this should be fixed, consider the below example,
which currently requires listing Column explicitly:
{code:java}
def listlike(value):
# Column unfortunately implements __iter__ just to raise a TypeError.
# This breaks the iterable contract and should be fixed in Spark proper.
return isinstance(value, collections.Iterable) and not isinstance(value,
(str, bytes, pyspark.sql.Column))
{code}
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