spark-instrumented-optimizer/python/pyspark/sql/pandas/map_ops.py
HyukjinKwon 3959f0d987 [SPARK-33250][PYTHON][DOCS] Migration to NumPy documentation style in SQL (pyspark.sql.*)
### What changes were proposed in this pull request?

This PR proposes to migrate to [NumPy documentation style](https://numpydoc.readthedocs.io/en/latest/format.html), see also SPARK-33243.
While I am migrating, I also fixed some Python type hints accordingly.

### Why are the changes needed?

For better documentation as text itself, and generated HTMLs

### Does this PR introduce _any_ user-facing change?

Yes, they will see a better format of HTMLs, and better text format. See SPARK-33243.

### How was this patch tested?

Manually tested via running `./dev/lint-python`.

Closes #30181 from HyukjinKwon/SPARK-33250.

Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
2020-11-03 10:00:49 +09:00

106 lines
3.7 KiB
Python

#
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# The ASF licenses this file to You under the Apache License, Version 2.0
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import sys
from pyspark.rdd import PythonEvalType
class PandasMapOpsMixin(object):
"""
Min-in for pandas map operations. Currently, only :class:`DataFrame`
can use this class.
"""
def mapInPandas(self, func, schema):
"""
Maps an iterator of batches in the current :class:`DataFrame` using a Python native
function that takes and outputs a pandas DataFrame, and returns the result as a
:class:`DataFrame`.
The function should take an iterator of `pandas.DataFrame`\\s and return
another iterator of `pandas.DataFrame`\\s. All columns are passed
together as an iterator of `pandas.DataFrame`\\s to the function and the
returned iterator of `pandas.DataFrame`\\s are combined as a :class:`DataFrame`.
Each `pandas.DataFrame` size can be controlled by
`spark.sql.execution.arrow.maxRecordsPerBatch`.
.. versionadded:: 3.0.0
Parameters
----------
func : function
a Python native function that takes an iterator of `pandas.DataFrame`\\s, and
outputs an iterator of `pandas.DataFrame`\\s.
schema : :class:`pyspark.sql.types.DataType` or str
the return type of the `func` in PySpark. The value can be either a
:class:`pyspark.sql.types.DataType` object or a DDL-formatted type string.
Examples
--------
>>> from pyspark.sql.functions import pandas_udf
>>> df = spark.createDataFrame([(1, 21), (2, 30)], ("id", "age"))
>>> def filter_func(iterator):
... for pdf in iterator:
... yield pdf[pdf.id == 1]
>>> df.mapInPandas(filter_func, df.schema).show() # doctest: +SKIP
+---+---+
| id|age|
+---+---+
| 1| 21|
+---+---+
Notes
-----
This API is experimental
See Also
--------
pyspark.sql.functions.pandas_udf
"""
from pyspark.sql import DataFrame
from pyspark.sql.pandas.functions import pandas_udf
assert isinstance(self, DataFrame)
udf = pandas_udf(
func, returnType=schema, functionType=PythonEvalType.SQL_MAP_PANDAS_ITER_UDF)
udf_column = udf(*[self[col] for col in self.columns])
jdf = self._jdf.mapInPandas(udf_column._jc.expr())
return DataFrame(jdf, self.sql_ctx)
def _test():
import doctest
from pyspark.sql import SparkSession
import pyspark.sql.pandas.map_ops
globs = pyspark.sql.pandas.map_ops.__dict__.copy()
spark = SparkSession.builder\
.master("local[4]")\
.appName("sql.pandas.map_ops tests")\
.getOrCreate()
globs['spark'] = spark
(failure_count, test_count) = doctest.testmod(
pyspark.sql.pandas.map_ops, globs=globs,
optionflags=doctest.ELLIPSIS | doctest.NORMALIZE_WHITESPACE | doctest.REPORT_NDIFF)
spark.stop()
if failure_count:
sys.exit(-1)
if __name__ == "__main__":
_test()