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author | Reynold Xin <rxin@apache.org> | 2014-05-25 16:04:17 -0700 |
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committer | Reynold Xin <rxin@apache.org> | 2014-05-25 16:04:23 -0700 |
commit | 8891495a187355934d240f47f390dbfa0c1efbe9 (patch) | |
tree | 62760e2c0be1eedff4bf9e2a72f343c1a0e97488 /python | |
parent | 33683974f7950b8881949f9c668c0b272b2b5f55 (diff) | |
download | spark-8891495a187355934d240f47f390dbfa0c1efbe9.tar.gz spark-8891495a187355934d240f47f390dbfa0c1efbe9.tar.bz2 spark-8891495a187355934d240f47f390dbfa0c1efbe9.zip |
Python docstring update for sql.py.
Mostly related to the following two rules in PEP8 and PEP257:
- Line length < 72 chars.
- First line should be a concise description of the function/class.
Author: Reynold Xin <rxin@apache.org>
Closes #869 from rxin/docstring-schemardd and squashes the following commits:
7cf0cbc [Reynold Xin] Updated sql.py for pep8 docstring.
0a4aef9 [Reynold Xin] Merge branch 'master' into docstring-schemardd
6678937 [Reynold Xin] Python docstring update for sql.py.
(cherry picked from commit 14f0358b2a0a9b92526bdad6d501ab753459eaa0)
Signed-off-by: Reynold Xin <rxin@apache.org>
Diffstat (limited to 'python')
-rw-r--r-- | python/pyspark/sql.py | 124 |
1 files changed, 63 insertions, 61 deletions
diff --git a/python/pyspark/sql.py b/python/pyspark/sql.py index fa4b9c7b68..b4e9618cc2 100644 --- a/python/pyspark/sql.py +++ b/python/pyspark/sql.py @@ -23,14 +23,14 @@ __all__ = ["SQLContext", "HiveContext", "LocalHiveContext", "TestHiveContext", " class SQLContext: - """ - Main entry point for SparkSQL functionality. A SQLContext can be used create L{SchemaRDD}s, - register L{SchemaRDD}s as tables, execute sql over tables, cache tables, and read parquet files. + """Main entry point for SparkSQL functionality. + + A SQLContext can be used create L{SchemaRDD}s, register L{SchemaRDD}s as + tables, execute SQL over tables, cache tables, and read parquet files. """ def __init__(self, sparkContext, sqlContext = None): - """ - Create a new SQLContext. + """Create a new SQLContext. @param sparkContext: The SparkContext to wrap. @@ -63,18 +63,20 @@ class SQLContext: @property def _ssql_ctx(self): - """ - Accessor for the JVM SparkSQL context. Subclasses can override this property to provide - their own JVM Contexts. + """Accessor for the JVM SparkSQL context. + + Subclasses can override this property to provide their own + JVM Contexts. """ if not hasattr(self, '_scala_SQLContext'): self._scala_SQLContext = self._jvm.SQLContext(self._jsc.sc()) return self._scala_SQLContext def inferSchema(self, rdd): - """ - Infer and apply a schema to an RDD of L{dict}s. We peek at the first row of the RDD to - determine the fields names and types, and then use that to extract all the dictionaries. + """Infer and apply a schema to an RDD of L{dict}s. + + We peek at the first row of the RDD to determine the fields names + and types, and then use that to extract all the dictionaries. >>> srdd = sqlCtx.inferSchema(rdd) >>> srdd.collect() == [{"field1" : 1, "field2" : "row1"}, {"field1" : 2, "field2": "row2"}, @@ -92,9 +94,10 @@ class SQLContext: return SchemaRDD(srdd, self) def registerRDDAsTable(self, rdd, tableName): - """ - Registers the given RDD as a temporary table in the catalog. Temporary tables exist only - during the lifetime of this instance of SQLContext. + """Registers the given RDD as a temporary table in the catalog. + + Temporary tables exist only during the lifetime of this instance of + SQLContext. >>> srdd = sqlCtx.inferSchema(rdd) >>> sqlCtx.registerRDDAsTable(srdd, "table1") @@ -106,8 +109,7 @@ class SQLContext: raise ValueError("Can only register SchemaRDD as table") def parquetFile(self, path): - """ - Loads a Parquet file, returning the result as a L{SchemaRDD}. + """Loads a Parquet file, returning the result as a L{SchemaRDD}. >>> import tempfile, shutil >>> parquetFile = tempfile.mkdtemp() @@ -122,8 +124,7 @@ class SQLContext: return SchemaRDD(jschema_rdd, self) def sql(self, sqlQuery): - """ - Executes a SQL query using Spark, returning the result as a L{SchemaRDD}. + """Return a L{SchemaRDD} representing the result of the given query. >>> srdd = sqlCtx.inferSchema(rdd) >>> sqlCtx.registerRDDAsTable(srdd, "table1") @@ -135,8 +136,7 @@ class SQLContext: return SchemaRDD(self._ssql_ctx.sql(sqlQuery), self) def table(self, tableName): - """ - Returns the specified table as a L{SchemaRDD}. + """Returns the specified table as a L{SchemaRDD}. >>> srdd = sqlCtx.inferSchema(rdd) >>> sqlCtx.registerRDDAsTable(srdd, "table1") @@ -147,23 +147,19 @@ class SQLContext: return SchemaRDD(self._ssql_ctx.table(tableName), self) def cacheTable(self, tableName): - """ - Caches the specified table in-memory. - """ + """Caches the specified table in-memory.""" self._ssql_ctx.cacheTable(tableName) def uncacheTable(self, tableName): - """ - Removes the specified table from the in-memory cache. - """ + """Removes the specified table from the in-memory cache.""" self._ssql_ctx.uncacheTable(tableName) class HiveContext(SQLContext): - """ - An instance of the Spark SQL execution engine that integrates with data stored in Hive. - Configuration for Hive is read from hive-site.xml on the classpath. It supports running both SQL - and HiveQL commands. + """A variant of Spark SQL that integrates with data stored in Hive. + + Configuration for Hive is read from hive-site.xml on the classpath. + It supports running both SQL and HiveQL commands. """ @property @@ -193,9 +189,10 @@ class HiveContext(SQLContext): class LocalHiveContext(HiveContext): - """ - Starts up an instance of hive where metadata is stored locally. An in-process metadata data is - created with data stored in ./metadata. Warehouse data is stored in in ./warehouse. + """Starts up an instance of hive where metadata is stored locally. + + An in-process metadata data is created with data stored in ./metadata. + Warehouse data is stored in in ./warehouse. >>> import os >>> hiveCtx = LocalHiveContext(sc) @@ -228,8 +225,10 @@ class TestHiveContext(HiveContext): # TODO: Investigate if it is more efficient to use a namedtuple. One problem is that named tuples # are custom classes that must be generated per Schema. class Row(dict): - """ - An extended L{dict} that takes a L{dict} in its constructor, and exposes those items as fields. + """A row in L{SchemaRDD}. + + An extended L{dict} that takes a L{dict} in its constructor, and + exposes those items as fields. >>> r = Row({"hello" : "world", "foo" : "bar"}) >>> r.hello @@ -245,13 +244,16 @@ class Row(dict): class SchemaRDD(RDD): - """ - An RDD of L{Row} objects that has an associated schema. The underlying JVM object is a SchemaRDD, - not a PythonRDD, so we can utilize the relational query api exposed by SparkSQL. + """An RDD of L{Row} objects that has an associated schema. - For normal L{pyspark.rdd.RDD} operations (map, count, etc.) the L{SchemaRDD} is not operated on - directly, as it's underlying implementation is a RDD composed of Java objects. Instead it is - converted to a PythonRDD in the JVM, on which Python operations can be done. + The underlying JVM object is a SchemaRDD, not a PythonRDD, so we can + utilize the relational query api exposed by SparkSQL. + + For normal L{pyspark.rdd.RDD} operations (map, count, etc.) the + L{SchemaRDD} is not operated on directly, as it's underlying + implementation is a RDD composed of Java objects. Instead it is + converted to a PythonRDD in the JVM, on which Python operations can + be done. """ def __init__(self, jschema_rdd, sql_ctx): @@ -266,8 +268,9 @@ class SchemaRDD(RDD): @property def _jrdd(self): - """ - Lazy evaluation of PythonRDD object. Only done when a user calls methods defined by the + """Lazy evaluation of PythonRDD object. + + Only done when a user calls methods defined by the L{pyspark.rdd.RDD} super class (map, filter, etc.). """ if not hasattr(self, '_lazy_jrdd'): @@ -279,10 +282,10 @@ class SchemaRDD(RDD): return self._jrdd.id() def saveAsParquetFile(self, path): - """ - Saves the contents of this L{SchemaRDD} as a parquet file, preserving the schema. Files - that are written out using this method can be read back in as a SchemaRDD using the - L{SQLContext.parquetFile} method. + """Save the contents as a Parquet file, preserving the schema. + + Files that are written out using this method can be read back in as + a SchemaRDD using the L{SQLContext.parquetFile} method. >>> import tempfile, shutil >>> parquetFile = tempfile.mkdtemp() @@ -296,9 +299,10 @@ class SchemaRDD(RDD): self._jschema_rdd.saveAsParquetFile(path) def registerAsTable(self, name): - """ - Registers this RDD as a temporary table using the given name. The lifetime of this temporary - table is tied to the L{SQLContext} that was used to create this SchemaRDD. + """Registers this RDD as a temporary table using the given name. + + The lifetime of this temporary table is tied to the L{SQLContext} + that was used to create this SchemaRDD. >>> srdd = sqlCtx.inferSchema(rdd) >>> srdd.registerAsTable("test") @@ -309,24 +313,22 @@ class SchemaRDD(RDD): self._jschema_rdd.registerAsTable(name) def insertInto(self, tableName, overwrite = False): - """ - Inserts the contents of this SchemaRDD into the specified table, - optionally overwriting any existing data. + """Inserts the contents of this SchemaRDD into the specified table. + + Optionally overwriting any existing data. """ self._jschema_rdd.insertInto(tableName, overwrite) def saveAsTable(self, tableName): - """ - Creates a new table with the contents of this SchemaRDD. - """ + """Creates a new table with the contents of this SchemaRDD.""" self._jschema_rdd.saveAsTable(tableName) def count(self): - """ - Return the number of elements in this RDD. Unlike the base RDD - implementation of count, this implementation leverages the query - optimizer to compute the count on the SchemaRDD, which supports - features such as filter pushdown. + """Return the number of elements in this RDD. + + Unlike the base RDD implementation of count, this implementation + leverages the query optimizer to compute the count on the SchemaRDD, + which supports features such as filter pushdown. >>> srdd = sqlCtx.inferSchema(rdd) >>> srdd.count() |