87be3641eb
### What changes were proposed in this pull request?
This PR is adding support duplicated column names for `toPandas` with Arrow execution.
### Why are the changes needed?
When we execute `toPandas()` with Arrow execution, it fails if the column names have duplicates.
```py
>>> spark.sql("select 1 v, 1 v").toPandas()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/path/to/lib/python3.7/site-packages/pyspark/sql/dataframe.py", line 2132, in toPandas
pdf = table.to_pandas()
File "pyarrow/array.pxi", line 441, in pyarrow.lib._PandasConvertible.to_pandas
File "pyarrow/table.pxi", line 1367, in pyarrow.lib.Table._to_pandas
File "/path/to/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 653, in table_to_blockmanager
columns = _deserialize_column_index(table, all_columns, column_indexes)
File "/path/to/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 704, in _deserialize_column_index
columns = _flatten_single_level_multiindex(columns)
File "/path/to/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 937, in _flatten_single_level_multiindex
raise ValueError('Found non-unique column index')
ValueError: Found non-unique column index
```
### Does this PR introduce any user-facing change?
Yes, previously we will face an error above, but after this PR, we will see the result:
```py
>>> spark.sql("select 1 v, 1 v").toPandas()
v v
0 1 1
```
### How was this patch tested?
Added and modified related tests.
Closes #28210 from ueshin/issues/SPARK-31441/to_pandas.
Authored-by: Takuya UESHIN <ueshin@databricks.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
|
||
|---|---|---|
| .. | ||
| docs | ||
| lib | ||
| pyspark | ||
| test_coverage | ||
| test_support | ||
| .coveragerc | ||
| .gitignore | ||
| MANIFEST.in | ||
| pylintrc | ||
| README.md | ||
| run-tests | ||
| run-tests-with-coverage | ||
| run-tests.py | ||
| setup.cfg | ||
| setup.py | ||
Apache Spark
Spark is a unified analytics engine for large-scale data processing. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Structured Streaming for stream processing.
Online Documentation
You can find the latest Spark documentation, including a programming guide, on the project web page
Python Packaging
This README file only contains basic information related to pip installed PySpark. This packaging is currently experimental and may change in future versions (although we will do our best to keep compatibility). Using PySpark requires the Spark JARs, and if you are building this from source please see the builder instructions at "Building Spark".
The Python packaging for Spark is not intended to replace all of the other use cases. This Python packaged version of Spark is suitable for interacting with an existing cluster (be it Spark standalone, YARN, or Mesos) - but does not contain the tools required to set up your own standalone Spark cluster. You can download the full version of Spark from the Apache Spark downloads page.
NOTE: If you are using this with a Spark standalone cluster you must ensure that the version (including minor version) matches or you may experience odd errors.
Python Requirements
At its core PySpark depends on Py4J, but some additional sub-packages have their own extra requirements for some features (including numpy, pandas, and pyarrow).