spark-instrumented-optimizer/python/pyspark/sql/tests/test_pandas_map.py
HyukjinKwon ab0890bdb1 [SPARK-28264][PYTHON][SQL] Support type hints in pandas UDF and rename/move inconsistent pandas UDF types
### What changes were proposed in this pull request?

This PR proposes to redesign pandas UDFs as described in [the proposal](https://docs.google.com/document/d/1-kV0FS_LF2zvaRh_GhkV32Uqksm_Sq8SvnBBmRyxm30/edit?usp=sharing).

```python
from pyspark.sql.functions import pandas_udf
import pandas as pd

pandas_udf("long")
def plug_one(s: pd.Series) -> pd.Series:
    return s + 1

spark.range(10).select(plug_one("id")).show()
```

```
+------------+
|plug_one(id)|
+------------+
|           1|
|           2|
|           3|
|           4|
|           5|
|           6|
|           7|
|           8|
|           9|
|          10|
+------------+
```

Note that, this PR address one of the future improvements described [here](https://docs.google.com/document/d/1-kV0FS_LF2zvaRh_GhkV32Uqksm_Sq8SvnBBmRyxm30/edit#heading=h.h3ncjpk6ujqu), "A couple of less-intuitive pandas UDF types" (by zero323) together.

In short,

- Adds new way with type hints as an alternative and experimental way.
    ```python
    pandas_udf(schema='...')
    def func(c1: Series, c2: Series) -> DataFrame:
        pass
    ```

- Replace and/or add an alias for three types below from UDF, and make them as separate standalone APIs. So, `pandas_udf` is now consistent with regular `udf`s and other expressions.

    `df.mapInPandas(udf)`  -replace-> `df.mapInPandas(f, schema)`
    `df.groupby.apply(udf)`  -alias-> `df.groupby.applyInPandas(f, schema)`
    `df.groupby.cogroup.apply(udf)`  -replace-> `df.groupby.cogroup.applyInPandas(f, schema)`

    *`df.groupby.apply` was added from 2.3 while the other were added in the master only.

- No deprecation for the existing ways for now.
    ```python
    pandas_udf(schema='...', functionType=PandasUDFType.SCALAR)
    def func(c1, c2):
        pass
    ```
If users are happy with this, I plan to deprecate the existing way and declare using type hints is not experimental anymore.

One design goal in this PR was that, avoid touching the internal (since we didn't deprecate the old ways for now), but supports type hints with a minimised changes only at the interface.

- Once we deprecate or remove the old ways, I think it requires another refactoring for the internal in the future. At the very least, we should rename internal pandas evaluation types.
- If users find this experimental type hints isn't quite helpful, we should simply revert the changes at the interface level.

### Why are the changes needed?

In order to address old design issues. Please see [the proposal](https://docs.google.com/document/d/1-kV0FS_LF2zvaRh_GhkV32Uqksm_Sq8SvnBBmRyxm30/edit?usp=sharing).

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

For behaviour changes, No.

It adds new ways to use pandas UDFs by using type hints. See below.

**SCALAR**:

```python
pandas_udf(schema='...')
def func(c1: Series, c2: DataFrame) -> Series:
    pass  # DataFrame represents a struct column
```

**SCALAR_ITER**:

```python
pandas_udf(schema='...')
def func(iter: Iterator[Tuple[Series, DataFrame, ...]]) -> Iterator[Series]:
    pass  # Same as SCALAR but wrapped by Iterator
```

**GROUPED_AGG**:

```python
pandas_udf(schema='...')
def func(c1: Series, c2: DataFrame) -> int:
    pass  # DataFrame represents a struct column
```

**GROUPED_MAP**:

This was added in Spark 2.3 as of SPARK-20396. As described above, it keeps the existing behaviour. Additionally, we now have a new alias `groupby.applyInPandas` for `groupby.apply`. See the example below:

```python
def func(pdf):
    return pdf

df.groupby("...").applyInPandas(func, schema=df.schema)
```

**MAP_ITER**: this is not a pandas UDF anymore

This was added in Spark 3.0 as of SPARK-28198; and this PR replaces the usages. See the example below:

```python
def func(iter):
    for df in iter:
        yield df

df.mapInPandas(func, df.schema)
```

**COGROUPED_MAP**: this is not a pandas UDF anymore

This was added in Spark 3.0 as of SPARK-27463; and this PR replaces the usages. See the example below:

```python
def asof_join(left, right):
    return pd.merge_asof(left, right, on="...", by="...")

 df1.groupby("...").cogroup(df2.groupby("...")).applyInPandas(asof_join, schema="...")
```

### How was this patch tested?

Unittests added and tested against Python 2.7, 3.6 and 3.7.

Closes #27165 from HyukjinKwon/revisit-pandas.

Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
2020-01-22 15:32:58 +09:00

130 lines
4.2 KiB
Python

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#
import os
import sys
import time
import unittest
if sys.version >= '3':
unicode = str
from pyspark.sql.functions import pandas_udf, PandasUDFType
from pyspark.testing.sqlutils import ReusedSQLTestCase, have_pandas, have_pyarrow, \
pandas_requirement_message, pyarrow_requirement_message
if have_pandas:
import pandas as pd
@unittest.skipIf(
not have_pandas or not have_pyarrow,
pandas_requirement_message or pyarrow_requirement_message)
class MapInPandasTests(ReusedSQLTestCase):
@classmethod
def setUpClass(cls):
ReusedSQLTestCase.setUpClass()
# Synchronize default timezone between Python and Java
cls.tz_prev = os.environ.get("TZ", None) # save current tz if set
tz = "America/Los_Angeles"
os.environ["TZ"] = tz
time.tzset()
cls.sc.environment["TZ"] = tz
cls.spark.conf.set("spark.sql.session.timeZone", tz)
@classmethod
def tearDownClass(cls):
del os.environ["TZ"]
if cls.tz_prev is not None:
os.environ["TZ"] = cls.tz_prev
time.tzset()
ReusedSQLTestCase.tearDownClass()
def test_map_partitions_in_pandas(self):
def func(iterator):
for pdf in iterator:
assert isinstance(pdf, pd.DataFrame)
assert pdf.columns == ['id']
yield pdf
df = self.spark.range(10)
actual = df.mapInPandas(func, 'id long').collect()
expected = df.collect()
self.assertEquals(actual, expected)
def test_multiple_columns(self):
data = [(1, "foo"), (2, None), (3, "bar"), (4, "bar")]
df = self.spark.createDataFrame(data, "a int, b string")
def func(iterator):
for pdf in iterator:
assert isinstance(pdf, pd.DataFrame)
assert [d.name for d in list(pdf.dtypes)] == ['int32', 'object']
yield pdf
actual = df.mapInPandas(func, df.schema).collect()
expected = df.collect()
self.assertEquals(actual, expected)
def test_different_output_length(self):
def func(iterator):
for _ in iterator:
yield pd.DataFrame({'a': list(range(100))})
df = self.spark.range(10)
actual = df.repartition(1).mapInPandas(func, 'a long').collect()
self.assertEquals(set((r.a for r in actual)), set(range(100)))
def test_empty_iterator(self):
def empty_iter(_):
return iter([])
self.assertEqual(
self.spark.range(10).mapInPandas(empty_iter, 'a int, b string').count(), 0)
def test_empty_rows(self):
def empty_rows(_):
return iter([pd.DataFrame({'a': []})])
self.assertEqual(
self.spark.range(10).mapInPandas(empty_rows, 'a int').count(), 0)
def test_chain_map_partitions_in_pandas(self):
def func(iterator):
for pdf in iterator:
assert isinstance(pdf, pd.DataFrame)
assert pdf.columns == ['id']
yield pdf
df = self.spark.range(10)
actual = df.mapInPandas(func, 'id long').mapInPandas(func, 'id long').collect()
expected = df.collect()
self.assertEquals(actual, expected)
if __name__ == "__main__":
from pyspark.sql.tests.test_pandas_map import *
try:
import xmlrunner
testRunner = xmlrunner.XMLTestRunner(output='target/test-reports', verbosity=2)
except ImportError:
testRunner = None
unittest.main(testRunner=testRunner, verbosity=2)