srchilukoori commented on code in PR #43972: URL: https://github.com/apache/spark/pull/43972#discussion_r1594759835
########## python/docs/source/user_guide/basic_dataframe_operations.rst: ########## @@ -0,0 +1,169 @@ +.. 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. + +========================== +Basic DataFrame Operations +========================== + +.. currentmodule:: pyspark.sql + +Select +------ + +Projects a set of expressions and returns a new :class:`DataFrame`. +For more detailed usage methods, please refer to :meth:`DataFrame.select`. + +Select all columns +~~~~~~~~~~~~~~~~~~ + +.. code-block:: python + + >>> df = spark.createDataFrame([(2, "Alice"), (5, "Bob")], schema=["age", "name"]) + >>> df.select('*').show() + +---+-----+ + |age| name| + +---+-----+ + | 2|Alice| + | 5| Bob| + +---+-----+ + + +Select by column names(string) or expressions (:class:`Column`) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. code-block:: python + + >>> df = spark.createDataFrame([(2, "Alice"), (5, "Bob")], schema=["age", "name"]) + >>> df.select('name', (df.age + 10).alias('age')).show() + +-----+---+ + | name|age| + +-----+---+ + |Alice| 12| + | Bob| 15| + +-----+---+ + + +Filter +------ + +Filters rows using the given condition. +For more detailed usage methods, please refer to :meth:`DataFrame.filter`. + +Filter by :class:`Column` instances +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. code-block:: python + + >>> df = spark.createDataFrame([(2, "Alice", "Math"), (5, "Bob", "Physics"), + ... (7, "Charlie", "Chemistry")], schema=["age", "name", "subject"]) + >>> df.filter(df.age > 3).show() + +---+-------+---------+ + |age| name| subject| + +---+-------+---------+ + | 5| Bob| Physics| + | 7|Charlie|Chemistry| + +---+-------+---------+ + + +Filter by SQL expression in a string +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. code-block:: python + + >>> df = spark.createDataFrame([(2, "Alice", "Math"), (5, "Bob", "Physics"), (7, "Charlie", "Chemistry")], + ... schema=["age", "name", "subject"]) + >>> df.filter("age > 3").show() + +---+-------+---------+ + |age| name| subject| + +---+-------+---------+ + | 5| Bob| Physics| + | 7|Charlie|Chemistry| + +---+-------+---------+ + + +Collect +------- + +Returns all the records in the DataFrame as a list of :class:`Row`. +For more detailed usage methods, please refer to :meth:`DataFrame.collect`. + +.. code-block:: python + + >>> df = spark.createDataFrame([(14, "Tom"), (23, "Alice"), (16, "Bob")], ["age", "name"]) + >>> df.collect() + [Row(age=14, name='Tom'), Row(age=23, name='Alice'), Row(age=16, name='Bob')] + Review Comment: @panbingkun Could you add a warning for this function as well. Since collect pulls the data into the driver and has a potential to kill it if the dataset is large. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
