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internal.py
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internal.py
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#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""
An internal immutable DataFrame with some metadata to manage indexes.
"""
import re
from typing import Any, Dict, List, Optional, Sequence, Tuple, Union, TYPE_CHECKING, cast
import numpy as np
import pandas as pd
from pandas.api.types import CategoricalDtype # noqa: F401
from pyspark._globals import _NoValue, _NoValueType
from pyspark.sql import functions as F, Column, DataFrame as SparkDataFrame, Window
from pyspark.sql.types import ( # noqa: F401
BooleanType,
DataType,
LongType,
StructField,
StructType,
StringType,
)
from pyspark.sql.utils import is_timestamp_ntz_preferred
# For running doctests and reference resolution in PyCharm.
from pyspark import pandas as ps
from pyspark.pandas._typing import Label
if TYPE_CHECKING:
# This is required in old Python 3.5 to prevent circular reference.
from pyspark.pandas.series import Series
from pyspark.pandas.spark.utils import as_nullable_spark_type, force_decimal_precision_scale
from pyspark.pandas.data_type_ops.base import DataTypeOps
from pyspark.pandas.typedef import (
Dtype,
as_spark_type,
extension_dtypes,
infer_pd_series_spark_type,
spark_type_to_pandas_dtype,
)
from pyspark.pandas.utils import (
column_labels_level,
default_session,
is_name_like_tuple,
is_testing,
lazy_property,
name_like_string,
scol_for,
spark_column_equals,
)
# A function to turn given numbers to Spark columns that represent pandas-on-Spark index.
SPARK_INDEX_NAME_FORMAT = "__index_level_{}__".format
SPARK_DEFAULT_INDEX_NAME = SPARK_INDEX_NAME_FORMAT(0)
# A pattern to check if the name of a Spark column is a pandas-on-Spark index name or not.
SPARK_INDEX_NAME_PATTERN = re.compile(r"__index_level_[0-9]+__")
NATURAL_ORDER_COLUMN_NAME = "__natural_order__"
HIDDEN_COLUMNS = {NATURAL_ORDER_COLUMN_NAME}
DEFAULT_SERIES_NAME = 0
SPARK_DEFAULT_SERIES_NAME = str(DEFAULT_SERIES_NAME)
class InternalField:
"""
The internal field to store the dtype as well as the Spark's StructField optionally.
Parameters
----------
dtype : numpy.dtype or pandas' ExtensionDtype
The dtype for the field
struct_field : StructField, optional
The `StructField` for the field. If None, InternalFrame will properly set.
"""
def __init__(self, dtype: Dtype, struct_field: Optional[StructField] = None):
self._dtype = dtype
self._struct_field = struct_field
@staticmethod
def from_struct_field(
struct_field: StructField, *, use_extension_dtypes: bool = False
) -> "InternalField":
"""
Returns a new InternalField object created from the given StructField.
The dtype will be inferred from the data type of the given StructField.
Parameters
----------
struct_field : StructField
The StructField used to create a new InternalField object.
use_extension_dtypes : bool
If True, try to use the extension dtypes.
Returns
-------
InternalField
"""
return InternalField(
dtype=spark_type_to_pandas_dtype(
struct_field.dataType, use_extension_dtypes=use_extension_dtypes
),
struct_field=struct_field,
)
@property
def dtype(self) -> Dtype:
"""Return the dtype for the field."""
return self._dtype
@property
def struct_field(self) -> Optional[StructField]:
"""Return the StructField for the field."""
return self._struct_field
@property
def name(self) -> str:
"""Return the field name if the StructField exists."""
assert self.struct_field is not None
return self.struct_field.name
@property
def spark_type(self) -> DataType:
"""Return the spark data type for the field if the StructField exists."""
assert self.struct_field is not None
return self.struct_field.dataType
@property
def nullable(self) -> bool:
"""Return the nullability for the field if the StructField exists."""
assert self.struct_field is not None
return self.struct_field.nullable
@property
def metadata(self) -> Dict[str, Any]:
"""Return the metadata for the field if the StructField exists."""
assert self.struct_field is not None
return self.struct_field.metadata
@property
def is_extension_dtype(self) -> bool:
"""Return whether the dtype for the field is an extension type or not."""
return isinstance(self.dtype, extension_dtypes)
def normalize_spark_type(self) -> "InternalField":
"""Return a new InternalField object with normalized Spark data type."""
assert self.struct_field is not None
return self.copy(
spark_type=force_decimal_precision_scale(as_nullable_spark_type(self.spark_type)),
nullable=True,
)
def copy(
self,
*,
name: Union[str, _NoValueType] = _NoValue,
dtype: Union[Dtype, _NoValueType] = _NoValue,
spark_type: Union[DataType, _NoValueType] = _NoValue,
nullable: Union[bool, _NoValueType] = _NoValue,
metadata: Union[Optional[Dict[str, Any]], _NoValueType] = _NoValue,
) -> "InternalField":
"""Copy the InternalField object."""
if name is _NoValue:
name = self.name
if dtype is _NoValue:
dtype = self.dtype
if spark_type is _NoValue:
spark_type = self.spark_type
if nullable is _NoValue:
nullable = self.nullable
if metadata is _NoValue:
metadata = self.metadata
return InternalField(
dtype=cast(Dtype, dtype),
struct_field=StructField(
name=cast(str, name),
dataType=cast(DataType, spark_type),
nullable=cast(bool, nullable),
metadata=cast(Optional[Dict[str, Any]], metadata),
),
)
def __eq__(self, other: Any) -> bool:
return (
isinstance(other, InternalField)
and self.dtype == other.dtype
and self.struct_field == other.struct_field
)
def __repr__(self) -> str:
return "InternalField(dtype={dtype}, struct_field={struct_field})".format(
dtype=self.dtype, struct_field=self.struct_field
)
class InternalFrame:
"""
The internal immutable DataFrame which manages Spark DataFrame and column names and index
information.
.. note:: this is an internal class. It is not supposed to be exposed to users and users
should not directly access to it.
The internal immutable DataFrame represents the index information for a DataFrame it belongs to.
For instance, if we have a pandas-on-Spark DataFrame as below, pandas DataFrame does not
store the index as columns.
>>> psdf = ps.DataFrame({
... 'A': [1, 2, 3, 4],
... 'B': [5, 6, 7, 8],
... 'C': [9, 10, 11, 12],
... 'D': [13, 14, 15, 16],
... 'E': [17, 18, 19, 20]}, columns = ['A', 'B', 'C', 'D', 'E'])
>>> psdf # doctest: +NORMALIZE_WHITESPACE
A B C D E
0 1 5 9 13 17
1 2 6 10 14 18
2 3 7 11 15 19
3 4 8 12 16 20
However, all columns including index column are also stored in Spark DataFrame internally
as below.
>>> psdf._internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+-----------------+---+---+---+---+---+
|__index_level_0__| A| B| C| D| E|
+-----------------+---+---+---+---+---+
| 0| 1| 5| 9| 13| 17|
| 1| 2| 6| 10| 14| 18|
| 2| 3| 7| 11| 15| 19|
| 3| 4| 8| 12| 16| 20|
+-----------------+---+---+---+---+---+
To fill this gap, the current metadata is used by mapping Spark's internal column
to pandas-on-Spark's index. See the method below:
* `spark_frame` represents the internal Spark DataFrame
* `data_spark_column_names` represents non-indexing Spark column names
* `data_spark_columns` represents non-indexing Spark columns
* `data_fields` represents non-indexing InternalFields
* `index_spark_column_names` represents internal index Spark column names
* `index_spark_columns` represents internal index Spark columns
* `index_fields` represents index InternalFields
* `spark_column_names` represents all columns
* `index_names` represents the external index name as a label
* `to_internal_spark_frame` represents Spark DataFrame derived by the metadata. Includes index.
* `to_pandas_frame` represents pandas DataFrame derived by the metadata
>>> internal = psdf._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+---+---+---+---+---+-----------------+
|__index_level_0__| A| B| C| D| E|__natural_order__|
+-----------------+---+---+---+---+---+-----------------+
| 0| 1| 5| 9| 13| 17| ...|
| 1| 2| 6| 10| 14| 18| ...|
| 2| 3| 7| 11| 15| 19| ...|
| 3| 4| 8| 12| 16| 20| ...|
+-----------------+---+---+---+---+---+-----------------+
>>> internal.data_spark_column_names
['A', 'B', 'C', 'D', 'E']
>>> internal.index_spark_column_names
['__index_level_0__']
>>> internal.spark_column_names
['__index_level_0__', 'A', 'B', 'C', 'D', 'E']
>>> internal.index_names
[None]
>>> internal.data_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=int64, struct_field=StructField('A', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('B', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('C', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('D', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('E', LongType(), False))]
>>> internal.index_fields
[InternalField(dtype=int64, struct_field=StructField('__index_level_0__', LongType(), False))]
>>> internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+-----------------+---+---+---+---+---+
|__index_level_0__| A| B| C| D| E|
+-----------------+---+---+---+---+---+
| 0| 1| 5| 9| 13| 17|
| 1| 2| 6| 10| 14| 18|
| 2| 3| 7| 11| 15| 19|
| 3| 4| 8| 12| 16| 20|
+-----------------+---+---+---+---+---+
>>> internal.to_pandas_frame
A B C D E
0 1 5 9 13 17
1 2 6 10 14 18
2 3 7 11 15 19
3 4 8 12 16 20
In case that index is set to one of the existing columns as below:
>>> psdf1 = psdf.set_index("A")
>>> psdf1 # doctest: +NORMALIZE_WHITESPACE
B C D E
A
1 5 9 13 17
2 6 10 14 18
3 7 11 15 19
4 8 12 16 20
>>> psdf1._internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+---+---+---+---+---+
| A| B| C| D| E|
+---+---+---+---+---+
| 1| 5| 9| 13| 17|
| 2| 6| 10| 14| 18|
| 3| 7| 11| 15| 19|
| 4| 8| 12| 16| 20|
+---+---+---+---+---+
>>> internal = psdf1._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+---+---+---+---+---+-----------------+
|__index_level_0__| A| B| C| D| E|__natural_order__|
+-----------------+---+---+---+---+---+-----------------+
| 0| 1| 5| 9| 13| 17| ...|
| 1| 2| 6| 10| 14| 18| ...|
| 2| 3| 7| 11| 15| 19| ...|
| 3| 4| 8| 12| 16| 20| ...|
+-----------------+---+---+---+---+---+-----------------+
>>> internal.data_spark_column_names
['B', 'C', 'D', 'E']
>>> internal.index_spark_column_names
['A']
>>> internal.spark_column_names
['A', 'B', 'C', 'D', 'E']
>>> internal.index_names
[('A',)]
>>> internal.data_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=int64, struct_field=StructField('B', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('C', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('D', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('E', LongType(), False))]
>>> internal.index_fields
[InternalField(dtype=int64, struct_field=StructField('A', LongType(), False))]
>>> internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+---+---+---+---+---+
| A| B| C| D| E|
+---+---+---+---+---+
| 1| 5| 9| 13| 17|
| 2| 6| 10| 14| 18|
| 3| 7| 11| 15| 19|
| 4| 8| 12| 16| 20|
+---+---+---+---+---+
>>> internal.to_pandas_frame # doctest: +NORMALIZE_WHITESPACE
B C D E
A
1 5 9 13 17
2 6 10 14 18
3 7 11 15 19
4 8 12 16 20
In case that index becomes a multi index as below:
>>> psdf2 = psdf.set_index("A", append=True)
>>> psdf2 # doctest: +NORMALIZE_WHITESPACE
B C D E
A
0 1 5 9 13 17
1 2 6 10 14 18
2 3 7 11 15 19
3 4 8 12 16 20
>>> psdf2._internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+-----------------+---+---+---+---+---+
|__index_level_0__| A| B| C| D| E|
+-----------------+---+---+---+---+---+
| 0| 1| 5| 9| 13| 17|
| 1| 2| 6| 10| 14| 18|
| 2| 3| 7| 11| 15| 19|
| 3| 4| 8| 12| 16| 20|
+-----------------+---+---+---+---+---+
>>> internal = psdf2._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+---+---+---+---+---+-----------------+
|__index_level_0__| A| B| C| D| E|__natural_order__|
+-----------------+---+---+---+---+---+-----------------+
| 0| 1| 5| 9| 13| 17| ...|
| 1| 2| 6| 10| 14| 18| ...|
| 2| 3| 7| 11| 15| 19| ...|
| 3| 4| 8| 12| 16| 20| ...|
+-----------------+---+---+---+---+---+-----------------+
>>> internal.data_spark_column_names
['B', 'C', 'D', 'E']
>>> internal.index_spark_column_names
['__index_level_0__', 'A']
>>> internal.spark_column_names
['__index_level_0__', 'A', 'B', 'C', 'D', 'E']
>>> internal.index_names
[None, ('A',)]
>>> internal.data_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=int64, struct_field=StructField('B', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('C', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('D', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('E', LongType(), False))]
>>> internal.index_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=int64, struct_field=StructField('__index_level_0__', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('A', LongType(), False))]
>>> internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+-----------------+---+---+---+---+---+
|__index_level_0__| A| B| C| D| E|
+-----------------+---+---+---+---+---+
| 0| 1| 5| 9| 13| 17|
| 1| 2| 6| 10| 14| 18|
| 2| 3| 7| 11| 15| 19|
| 3| 4| 8| 12| 16| 20|
+-----------------+---+---+---+---+---+
>>> internal.to_pandas_frame # doctest: +NORMALIZE_WHITESPACE
B C D E
A
0 1 5 9 13 17
1 2 6 10 14 18
2 3 7 11 15 19
3 4 8 12 16 20
For multi-level columns, it also holds column_labels
>>> columns = pd.MultiIndex.from_tuples([('X', 'A'), ('X', 'B'),
... ('Y', 'C'), ('Y', 'D')])
>>> psdf3 = ps.DataFrame([
... [1, 2, 3, 4],
... [5, 6, 7, 8],
... [9, 10, 11, 12],
... [13, 14, 15, 16],
... [17, 18, 19, 20]], columns = columns)
>>> psdf3 # doctest: +NORMALIZE_WHITESPACE
X Y
A B C D
0 1 2 3 4
1 5 6 7 8
2 9 10 11 12
3 13 14 15 16
4 17 18 19 20
>>> internal = psdf3._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+------+------+------+------+-----------------+
|__index_level_0__|(X, A)|(X, B)|(Y, C)|(Y, D)|__natural_order__|
+-----------------+------+------+------+------+-----------------+
| 0| 1| 2| 3| 4| ...|
| 1| 5| 6| 7| 8| ...|
| 2| 9| 10| 11| 12| ...|
| 3| 13| 14| 15| 16| ...|
| 4| 17| 18| 19| 20| ...|
+-----------------+------+------+------+------+-----------------+
>>> internal.data_spark_column_names
['(X, A)', '(X, B)', '(Y, C)', '(Y, D)']
>>> internal.column_labels
[('X', 'A'), ('X', 'B'), ('Y', 'C'), ('Y', 'D')]
For Series, it also holds scol to represent the column.
>>> psseries = psdf1.B
>>> psseries
A
1 5
2 6
3 7
4 8
Name: B, dtype: int64
>>> internal = psseries._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+---+---+---+---+---+-----------------+
|__index_level_0__| A| B| C| D| E|__natural_order__|
+-----------------+---+---+---+---+---+-----------------+
| 0| 1| 5| 9| 13| 17| ...|
| 1| 2| 6| 10| 14| 18| ...|
| 2| 3| 7| 11| 15| 19| ...|
| 3| 4| 8| 12| 16| 20| ...|
+-----------------+---+---+---+---+---+-----------------+
>>> internal.data_spark_column_names
['B']
>>> internal.index_spark_column_names
['A']
>>> internal.spark_column_names
['A', 'B']
>>> internal.index_names
[('A',)]
>>> internal.data_fields
[InternalField(dtype=int64, struct_field=StructField('B', LongType(), False))]
>>> internal.index_fields
[InternalField(dtype=int64, struct_field=StructField('A', LongType(), False))]
>>> internal.to_internal_spark_frame.show() # doctest: +NORMALIZE_WHITESPACE
+---+---+
| A| B|
+---+---+
| 1| 5|
| 2| 6|
| 3| 7|
| 4| 8|
+---+---+
>>> internal.to_pandas_frame # doctest: +NORMALIZE_WHITESPACE
B
A
1 5
2 6
3 7
4 8
"""
def __init__(
self,
spark_frame: SparkDataFrame,
index_spark_columns: Optional[List[Column]],
index_names: Optional[List[Optional[Label]]] = None,
index_fields: Optional[List[InternalField]] = None,
column_labels: Optional[List[Label]] = None,
data_spark_columns: Optional[List[Column]] = None,
data_fields: Optional[List[InternalField]] = None,
column_label_names: Optional[List[Optional[Label]]] = None,
):
"""
Create a new internal immutable DataFrame to manage Spark DataFrame, column fields and
index fields and names.
:param spark_frame: Spark DataFrame to be managed.
:param index_spark_columns: list of Spark Column
Spark Columns for the index.
:param index_names: list of tuples
the index names.
:param index_fields: list of InternalField
the InternalFields for the index columns
:param column_labels: list of tuples with the same length
The multi-level values in the tuples.
:param data_spark_columns: list of Spark Column
Spark Columns to appear as columns. If this is None, calculated
from spark_frame.
:param data_fields: list of InternalField
the InternalFields for the data columns
:param column_label_names: Names for each of the column index levels.
See the examples below to refer what each parameter means.
>>> column_labels = pd.MultiIndex.from_tuples(
... [('a', 'x'), ('a', 'y'), ('b', 'z')], names=["column_labels_a", "column_labels_b"])
>>> row_index = pd.MultiIndex.from_tuples(
... [('foo', 'bar'), ('foo', 'bar'), ('zoo', 'bar')],
... names=["row_index_a", "row_index_b"])
>>> psdf = ps.DataFrame(
... [[1, 2, 3], [4, 5, 6], [7, 8, 9]], index=row_index, columns=column_labels)
>>> psdf.set_index(('a', 'x'), append=True, inplace=True)
>>> psdf # doctest: +NORMALIZE_WHITESPACE
column_labels_a a b
column_labels_b y z
row_index_a row_index_b (a, x)
foo bar 1 2 3
4 5 6
zoo bar 7 8 9
>>> internal = psdf._internal
>>> internal.spark_frame.show() # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
+-----------------+-----------------+------+------+------+...
|__index_level_0__|__index_level_1__|(a, x)|(a, y)|(b, z)|...
+-----------------+-----------------+------+------+------+...
| foo| bar| 1| 2| 3|...
| foo| bar| 4| 5| 6|...
| zoo| bar| 7| 8| 9|...
+-----------------+-----------------+------+------+------+...
>>> internal.index_spark_columns # doctest: +SKIP
[Column<'__index_level_0__'>, Column<'__index_level_1__'>, Column<'(a, x)'>]
>>> internal.index_names
[('row_index_a',), ('row_index_b',), ('a', 'x')]
>>> internal.index_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=object,
struct_field=StructField('__index_level_0__', StringType(), False)),
InternalField(dtype=object,
struct_field=StructField('__index_level_1__', StringType(), False)),
InternalField(dtype=int64,
struct_field=StructField('(a, x)', LongType(), False))]
>>> internal.column_labels
[('a', 'y'), ('b', 'z')]
>>> internal.data_spark_columns # doctest: +SKIP
[Column<'(a, y)'>, Column<'(b, z)'>]
>>> internal.data_fields # doctest: +NORMALIZE_WHITESPACE
[InternalField(dtype=int64, struct_field=StructField('(a, y)', LongType(), False)),
InternalField(dtype=int64, struct_field=StructField('(b, z)', LongType(), False))]
>>> internal.column_label_names
[('column_labels_a',), ('column_labels_b',)]
"""
assert isinstance(spark_frame, SparkDataFrame)
assert not spark_frame.isStreaming, "pandas-on-Spark does not support Structured Streaming."
if not index_spark_columns:
if data_spark_columns is not None:
if column_labels is not None:
data_spark_columns = [
scol.alias(name_like_string(label))
for scol, label in zip(data_spark_columns, column_labels)
]
spark_frame = spark_frame.select(data_spark_columns)
assert not any(SPARK_INDEX_NAME_PATTERN.match(name) for name in spark_frame.columns), (
"Index columns should not appear in columns of the Spark DataFrame. Avoid "
"index column names [%s]." % SPARK_INDEX_NAME_PATTERN
)
# Create default index.
spark_frame = InternalFrame.attach_default_index(spark_frame)
index_spark_columns = [scol_for(spark_frame, SPARK_DEFAULT_INDEX_NAME)]
index_fields = [
InternalField.from_struct_field(
StructField(SPARK_DEFAULT_INDEX_NAME, LongType(), nullable=False)
)
]
if data_spark_columns is not None:
data_struct_fields = [
field
for field in spark_frame.schema.fields
if field.name != SPARK_DEFAULT_INDEX_NAME
]
data_spark_columns = [
scol_for(spark_frame, field.name) for field in data_struct_fields
]
if data_fields is not None:
data_fields = [
field.copy(
name=name_like_string(struct_field.name),
)
for field, struct_field in zip(data_fields, data_struct_fields)
]
if NATURAL_ORDER_COLUMN_NAME not in spark_frame.columns:
spark_frame = spark_frame.withColumn(
NATURAL_ORDER_COLUMN_NAME, F.monotonically_increasing_id()
)
self._sdf: SparkDataFrame = spark_frame
# index_spark_columns
assert all(
isinstance(index_scol, Column) for index_scol in index_spark_columns
), index_spark_columns
self._index_spark_columns: List[Column] = index_spark_columns
# data_spark_columns
if data_spark_columns is None:
data_spark_columns = [
scol_for(spark_frame, col)
for col in spark_frame.columns
if all(
not spark_column_equals(scol_for(spark_frame, col), index_scol)
for index_scol in index_spark_columns
)
and col not in HIDDEN_COLUMNS
]
else:
assert all(isinstance(scol, Column) for scol in data_spark_columns)
self._data_spark_columns: List[Column] = data_spark_columns
# fields
if index_fields is None:
index_fields = [None] * len(index_spark_columns)
if data_fields is None:
data_fields = [None] * len(data_spark_columns)
assert len(index_spark_columns) == len(index_fields), (
len(index_spark_columns),
len(index_fields),
)
assert len(data_spark_columns) == len(data_fields), (
len(data_spark_columns),
len(data_fields),
)
if any(field is None or field.struct_field is None for field in index_fields) and any(
field is None or field.struct_field is None for field in data_fields
):
schema = spark_frame.select(index_spark_columns + data_spark_columns).schema
fields = [
InternalField.from_struct_field(struct_field)
if field is None
else InternalField(field.dtype, struct_field)
if field.struct_field is None
else field
for field, struct_field in zip(index_fields + data_fields, schema.fields)
]
index_fields = fields[: len(index_spark_columns)]
data_fields = fields[len(index_spark_columns) :]
elif any(field is None or field.struct_field is None for field in index_fields):
schema = spark_frame.select(index_spark_columns).schema
index_fields = [
InternalField.from_struct_field(struct_field)
if field is None
else InternalField(field.dtype, struct_field)
if field.struct_field is None
else field
for field, struct_field in zip(index_fields, schema.fields)
]
elif any(field is None or field.struct_field is None for field in data_fields):
schema = spark_frame.select(data_spark_columns).schema
data_fields = [
InternalField.from_struct_field(struct_field)
if field is None
else InternalField(field.dtype, struct_field)
if field.struct_field is None
else field
for field, struct_field in zip(data_fields, schema.fields)
]
assert all(
isinstance(ops.dtype, Dtype.__args__) # type: ignore[attr-defined]
and (
ops.dtype == np.dtype("object")
or as_spark_type(ops.dtype, raise_error=False) is not None
)
for ops in index_fields
), index_fields
if is_testing():
struct_fields = spark_frame.select(index_spark_columns).schema.fields
assert all(
index_field.struct_field == struct_field
for index_field, struct_field in zip(index_fields, struct_fields)
), (index_fields, struct_fields)
self._index_fields: List[InternalField] = index_fields
assert all(
isinstance(ops.dtype, Dtype.__args__) # type: ignore[attr-defined]
and (
ops.dtype == np.dtype("object")
or as_spark_type(ops.dtype, raise_error=False) is not None
)
for ops in data_fields
), data_fields
if is_testing():
struct_fields = spark_frame.select(data_spark_columns).schema.fields
assert all(
data_field.struct_field == struct_field
for data_field, struct_field in zip(data_fields, struct_fields)
), (data_fields, struct_fields)
self._data_fields: List[InternalField] = data_fields
# index_names
if not index_names:
index_names = [None] * len(index_spark_columns)
assert len(index_spark_columns) == len(index_names), (
len(index_spark_columns),
len(index_names),
)
assert all(
is_name_like_tuple(index_name, check_type=True) for index_name in index_names
), index_names
self._index_names: List[Optional[Label]] = index_names
# column_labels
if column_labels is None:
column_labels = [(col,) for col in spark_frame.select(self._data_spark_columns).columns]
else:
assert len(column_labels) == len(self._data_spark_columns), (
len(column_labels),
len(self._data_spark_columns),
)
if len(column_labels) == 1:
column_label = column_labels[0]
assert is_name_like_tuple(column_label, check_type=True), column_label
else:
assert all(
is_name_like_tuple(column_label, check_type=True)
for column_label in column_labels
), column_labels
assert len(set(len(label) for label in column_labels)) <= 1, column_labels
self._column_labels: List[Label] = column_labels
# column_label_names
if column_label_names is None:
column_label_names = [None] * column_labels_level(self._column_labels)
else:
if len(self._column_labels) > 0:
assert len(column_label_names) == column_labels_level(self._column_labels), (
len(column_label_names),
column_labels_level(self._column_labels),
)
else:
assert len(column_label_names) > 0, len(column_label_names)
assert all(
is_name_like_tuple(column_label_name, check_type=True)
for column_label_name in column_label_names
), column_label_names
self._column_label_names: List[Optional[Label]] = column_label_names
@staticmethod
def attach_default_index(
sdf: SparkDataFrame, default_index_type: Optional[str] = None
) -> SparkDataFrame:
"""
This method attaches a default index to Spark DataFrame. Spark does not have the index
notion so corresponding column should be generated.
There are several types of default index can be configured by `compute.default_index_type`.
>>> spark_frame = ps.range(10).to_spark()
>>> spark_frame
DataFrame[id: bigint]
It adds the default index column '__index_level_0__'.
>>> spark_frame = InternalFrame.attach_default_index(spark_frame)
>>> spark_frame
DataFrame[__index_level_0__: bigint, id: bigint]
It throws an exception if the given column name already exists.
>>> InternalFrame.attach_default_index(spark_frame)
... # doctest: +ELLIPSIS
Traceback (most recent call last):
...
AssertionError: '__index_level_0__' already exists...
"""
index_column = SPARK_DEFAULT_INDEX_NAME
assert (
index_column not in sdf.columns
), "'%s' already exists in the Spark column names '%s'" % (index_column, sdf.columns)
if default_index_type is None:
default_index_type = ps.get_option("compute.default_index_type")
if default_index_type == "sequence":
return InternalFrame.attach_sequence_column(sdf, column_name=index_column)
elif default_index_type == "distributed-sequence":
return InternalFrame.attach_distributed_sequence_column(sdf, column_name=index_column)
elif default_index_type == "distributed":
return InternalFrame.attach_distributed_column(sdf, column_name=index_column)
else:
raise ValueError(
"'compute.default_index_type' should be one of 'sequence',"
" 'distributed-sequence' and 'distributed'"
)
@staticmethod
def attach_sequence_column(sdf: SparkDataFrame, column_name: str) -> SparkDataFrame:
scols = [scol_for(sdf, column) for column in sdf.columns]
sequential_index = (
F.row_number().over(Window.orderBy(F.monotonically_increasing_id())).cast("long") - 1
)
return sdf.select(sequential_index.alias(column_name), *scols)
@staticmethod
def attach_distributed_column(sdf: SparkDataFrame, column_name: str) -> SparkDataFrame:
scols = [scol_for(sdf, column) for column in sdf.columns]
jvm = sdf.sparkSession._jvm
tag = jvm.org.apache.spark.sql.catalyst.analysis.FunctionRegistry.FUNC_ALIAS()
jexpr = F.monotonically_increasing_id()._jc.expr()
jexpr.setTagValue(tag, "distributed_index")
return sdf.select(Column(jvm.Column(jexpr)).alias(column_name), *scols)
@staticmethod
def attach_distributed_sequence_column(sdf: SparkDataFrame, column_name: str) -> SparkDataFrame:
"""
This method attaches a Spark column that has a sequence in a distributed manner.
This is equivalent to the column assigned when default index type 'distributed-sequence'.
>>> sdf = ps.DataFrame(['a', 'b', 'c']).to_spark()
>>> sdf = InternalFrame.attach_distributed_sequence_column(sdf, column_name="sequence")
>>> sdf.show() # doctest: +NORMALIZE_WHITESPACE
+--------+---+
|sequence| 0|
+--------+---+
| 0| a|
| 1| b|
| 2| c|
+--------+---+
"""
if len(sdf.columns) > 0:
return SparkDataFrame(
sdf._jdf.toDF().withSequenceColumn(column_name),
sdf.sparkSession,
)
else:
cnt = sdf.count()
if cnt > 0:
return default_session().range(cnt).toDF(column_name)
else:
return default_session().createDataFrame(
[], schema=StructType().add(column_name, data_type=LongType(), nullable=False)
)
def spark_column_for(self, label: Label) -> Column:
"""Return Spark Column for the given column label."""
column_labels_to_scol = dict(zip(self.column_labels, self.data_spark_columns))
if label in column_labels_to_scol:
return column_labels_to_scol[label]
else:
raise KeyError(name_like_string(label))
def spark_column_name_for(self, label_or_scol: Union[Label, Column]) -> str:
"""Return the actual Spark column name for the given column label."""
if isinstance(label_or_scol, Column):
return self.spark_frame.select(label_or_scol).columns[0]
else:
return self.field_for(label_or_scol).name
def spark_type_for(self, label_or_scol: Union[Label, Column]) -> DataType:
"""Return DataType for the given column label."""
if isinstance(label_or_scol, Column):
return self.spark_frame.select(label_or_scol).schema[0].dataType
else:
return self.field_for(label_or_scol).spark_type
def spark_column_nullable_for(self, label_or_scol: Union[Label, Column]) -> bool:
"""Return nullability for the given column label."""
if isinstance(label_or_scol, Column):
return self.spark_frame.select(label_or_scol).schema[0].nullable
else:
return self.field_for(label_or_scol).nullable
def field_for(self, label: Label) -> InternalField:
"""Return InternalField for the given column label."""
column_labels_to_fields = dict(zip(self.column_labels, self.data_fields))
if label in column_labels_to_fields:
return column_labels_to_fields[label]
else:
raise KeyError(name_like_string(label))
@property
def spark_frame(self) -> SparkDataFrame:
"""Return the managed Spark DataFrame."""
return self._sdf
@lazy_property
def data_spark_column_names(self) -> List[str]:
"""Return the managed column field names."""
return [field.name for field in self.data_fields]
@property
def data_spark_columns(self) -> List[Column]:
"""Return Spark Columns for the managed data columns."""
return self._data_spark_columns
@property
def index_spark_column_names(self) -> List[str]:
"""Return the managed index field names."""
return [field.name for field in self.index_fields]
@property
def index_spark_columns(self) -> List[Column]:
"""Return Spark Columns for the managed index columns."""
return self._index_spark_columns
@lazy_property
def spark_column_names(self) -> List[str]:
"""Return all the field names including index field names."""
return self.spark_frame.select(self.spark_columns).columns
@lazy_property
def spark_columns(self) -> List[Column]:
"""Return Spark Columns for the managed columns including index columns."""
index_spark_columns = self.index_spark_columns
return index_spark_columns + [
spark_column
for spark_column in self.data_spark_columns