Github user jkbradley commented on a diff in the pull request: https://github.com/apache/spark/pull/11663#discussion_r56406647 --- Diff: python/pyspark/ml/param/__init__.py --- @@ -65,6 +72,106 @@ def __eq__(self, other): return False +class TypeConverters(object): + """ + .. note:: DeveloperApi + + Factory methods for common type conversion functions for `Param.typeConverter`. + + .. versionadded:: 2.0.0 + """ + + @staticmethod + def _is_numeric(value): + vtype = type(value) + return vtype == int or vtype == float or vtype == np.float64 \ + or vtype == np.int64 or vtype.__name__ == 'long' + + @staticmethod + def _can_convert_to_list(value): + vtype = type(value) + return vtype == list or vtype == np.ndarray or isinstance(value, Vector) + + @staticmethod + def identity(value): + """ + Dummy converter that just returns value. + """ + return value + + @staticmethod + def convertToList(value): + """ + Convert a value to a list, if possible. + """ + if type(value) == list: + return value + elif type(value) == np.ndarray: + return list(value) + elif isinstance(value, Vector): + return value.toArray() + else: + raise TypeError("Could not convert %s to list" % value) + + @staticmethod + def convertToListFloat(value): + """ + Convert a value to list of floats, if possible. + """ + if TypeConverters._can_convert_to_list(value) and \ + all(map(lambda v: TypeConverters._is_numeric(v), value)): + value = TypeConverters.convertToList(value) + return list(map(lambda v: float(v), value)) + else: + raise TypeError("Could not convert %s to list of floats" % value) + + @staticmethod + def convertToListInt(value): + """ + Convert a value to list of ints, if possible. + """ + if TypeConverters._can_convert_to_list(value) and \ + all(map(lambda v: TypeConverters._is_numeric(v), value)): --- End diff -- This too might not work with SparseVectors. It would also be nice to check that the value is an integer.
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