GitHub user jsnowacki opened a pull request: https://github.com/apache/spark/pull/19443
[SPARK-22212][SQL][PySpark] Some SQL functions in Python fail with string column name ## What changes were proposed in this pull request? The issue in JIRA: [SPARK-22212](https://issues.apache.org/jira/browse/SPARK-22212) Most of the functions in `pyspark.sql.functions` allow usage of both column name string and `Column` object. But there are some functions, like `trim`, that require to pass only `Column`. See below code for explanation. ``` >>> import pyspark.sql.functions as func >>> df = spark.createDataFrame([tuple(l) for l in "abcde"], ["text"]) >>> df.select(func.trim(df["text"])).show() +----------+ |trim(text)| +----------+ | a| | b| | c| | d| | e| +----------+ >>> df.select(func.trim("text")).show() [...] Py4JError: An error occurred while calling z:org.apache.spark.sql.functions.trim. Trace: py4j.Py4JException: Method trim([class java.lang.String]) does not exist at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:318) at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:339) at py4j.Gateway.invoke(Gateway.java:274) at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132) at py4j.commands.CallCommand.execute(CallCommand.java:79) at py4j.GatewayConnection.run(GatewayConnection.java:214) at java.lang.Thread.run(Thread.java:748) ``` This is because most of the Python function calls map column name to `Column` in the Python function mapping, but functions created via `_create_function` pass them as is, if they are not `Column`. On the other hand, few functions that require the column name has been moved `functions_by_column_name`, and are created by `_create_function_by_column_name`. Note that this is only Python-side fix. Some Scala functions still do not have method to call them by string column name. ## How was this patch tested? Additional Python tests where written to accommodate this. It was tested via `UnitTest` in IDE and the overall `python\run_tests` script. You can merge this pull request into a Git repository by running: $ git pull https://github.com/jsnowacki/spark-1 fix_func_str_to_col Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/19443.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #19443 ---- commit c5dbd50361a37e9833708dc8985345fbf537e8d9 Author: Jakub Nowacki <j.s.nowa...@gmail.com> Date: 2017-10-03T07:50:50Z [SPARK-22212] Fixing string to column mapping in Python functions commit 9e52c6380ae8787d20e3442cfaf42cfb70caf4dc Author: Jakub Nowacki <j.s.nowa...@gmail.com> Date: 2017-10-06T09:07:26Z [SPARK-22212] Calling functions by string column name fixed and tested ---- --- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org