zero323 commented on a change in pull request #27406:
[SPARK-30681][PYSPARK][SQL] Add higher order functions API to PySpark
URL: https://github.com/apache/spark/pull/27406#discussion_r373480230
##########
File path: python/pyspark/sql/column.py
##########
@@ -129,6 +129,111 @@ def _(self, other):
return _
+def _unresolved_named_lambda_variable(*name_parts):
+ """
+ Create o.a.s.sql.expressions.UnresolvedNamedLambdaVariable and
+ convert it to o.s.sql.Column
+
+ :param name_parts: str
+ """
+ sc = SparkContext._active_spark_context
+ name_parts_seq = _to_seq(sc, name_parts)
+ expressions = sc._jvm.org.apache.spark.sql.catalyst.expressions
+ return Column(
+ sc._jvm.Column(
+ expressions.UnresolvedNamedLambdaVariable(name_parts_seq)
+ )
+ )
+
+
+def _get_lambda_parameters(f):
+ import inspect
+
+ signature = inspect.signature(f)
+ parameters = signature.parameters.values()
+
+ # We should exclude functions that use
+ # variable args and keyword argnames
+ # as well as keyword only args
+ supported_parmeter_types = {
+ inspect.Parameter.POSITIONAL_OR_KEYWORD,
+ inspect.Parameter.POSITIONAL_ONLY,
+ }
+
+ # Validate that
+ # function arity is between 1 and 3
+ if not (1 <= len(parameters) <= 3):
+ raise ValueError(
+ "f should take between 1 and 3 arguments, but provided function
takes {}".format(
+ len(parameters)
+ )
+ )
+
+ # and all arguments can be used as positional
+ if not all(p.kind in supported_parmeter_types for p in parameters):
+ raise ValueError(
+ "f should use only POSITIONAL or POSITIONAL OR KEYWORD arguments"
+ )
+
+ return parameters
+
+
+def _get_lambda_parameters_legacy(f):
+ # TODO (SPARK-29909) Remove once 2.7 support is dropped
+ import inspect
+
+ spec = inspect.getargspec(f)
+ if not 1 <= len(spec.args) <= 3 or spec.varargs or spec.keywords:
+ raise ValueError(
+ "f should take between 1 and 3 arguments, but provided function
takes {}".format(
+ spec
+ )
+ )
+ return spec.args
+
+
+def _create_lambda(f, allowed_arities):
Review comment:
My reasoning was that we keep different `_to_*` functions directly related
to building internal Scala objects in `column.py` , and this seemed more like
one of these (functions I've included in `functions.py` are closer related to
utilities that are used to invoke `o.a.s.sql.functions`, which are already in
`functions.py` module).
But I don't have any strong feelings about it. I'll handle this in a moment.
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