# # 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. # import sys import itertools import warnings import random import os from tempfile import NamedTemporaryFile from itertools import imap from py4j.java_collections import ListConverter, MapConverter from pyspark.context import SparkContext from pyspark.rdd import RDD, _prepare_for_python_RDD from pyspark.serializers import BatchedSerializer, AutoBatchedSerializer, PickleSerializer, \ UTF8Deserializer from pyspark.storagelevel import StorageLevel from pyspark.traceback_utils import SCCallSiteSync from pyspark.sql.types import * from pyspark.sql.types import _create_cls, _parse_datatype_json_string __all__ = ["DataFrame", "GroupedData", "Column", "Dsl", "SchemaRDD"] class DataFrame(object): """A collection of rows that have the same columns. A :class:`DataFrame` is equivalent to a relational table in Spark SQL, and can be created using various functions in :class:`SQLContext`:: people = sqlContext.parquetFile("...") Once created, it can be manipulated using the various domain-specific-language (DSL) functions defined in: :class:`DataFrame`, :class:`Column`. To select a column from the data frame, use the apply method:: ageCol = people.age Note that the :class:`Column` type can also be manipulated through its various functions:: # The following creates a new column that increases everybody's age by 10. people.age + 10 A more concrete example:: # To create DataFrame using SQLContext people = sqlContext.parquetFile("...") department = sqlContext.parquetFile("...") people.filter(people.age > 30).join(department, people.deptId == department.id)) \ .groupBy(department.name, "gender").agg({"salary": "avg", "age": "max"}) """ def __init__(self, jdf, sql_ctx): self._jdf = jdf self.sql_ctx = sql_ctx self._sc = sql_ctx and sql_ctx._sc self.is_cached = False @property def rdd(self): """ Return the content of the :class:`DataFrame` as an :class:`RDD` of :class:`Row` s. """ if not hasattr(self, '_lazy_rdd'): jrdd = self._jdf.javaToPython() rdd = RDD(jrdd, self.sql_ctx._sc, BatchedSerializer(PickleSerializer())) schema = self.schema() def applySchema(it): cls = _create_cls(schema) return itertools.imap(cls, it) self._lazy_rdd = rdd.mapPartitions(applySchema) return self._lazy_rdd def toJSON(self, use_unicode=False): """Convert a DataFrame into a MappedRDD of JSON documents; one document per row. >>> df.toJSON().first() '{"age":2,"name":"Alice"}' """ rdd = self._jdf.toJSON() return RDD(rdd.toJavaRDD(), self._sc, UTF8Deserializer(use_unicode)) def saveAsParquetFile(self, path): """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 DataFrame using the L{SQLContext.parquetFile} method. >>> import tempfile, shutil >>> parquetFile = tempfile.mkdtemp() >>> shutil.rmtree(parquetFile) >>> df.saveAsParquetFile(parquetFile) >>> df2 = sqlCtx.parquetFile(parquetFile) >>> sorted(df2.collect()) == sorted(df.collect()) True """ self._jdf.saveAsParquetFile(path) def registerTempTable(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 DataFrame. >>> df.registerTempTable("people") >>> df2 = sqlCtx.sql("select * from people") >>> sorted(df.collect()) == sorted(df2.collect()) True """ self._jdf.registerTempTable(name) def registerAsTable(self, name): """DEPRECATED: use registerTempTable() instead""" warnings.warn("Use registerTempTable instead of registerAsTable.", DeprecationWarning) self.registerTempTable(name) def insertInto(self, tableName, overwrite=False): """Inserts the contents of this DataFrame into the specified table. Optionally overwriting any existing data. """ self._jdf.insertInto(tableName, overwrite) def _java_save_mode(self, mode): """Returns the Java save mode based on the Python save mode represented by a string. """ jSaveMode = self._sc._jvm.org.apache.spark.sql.SaveMode jmode = jSaveMode.ErrorIfExists mode = mode.lower() if mode == "append": jmode = jSaveMode.Append elif mode == "overwrite": jmode = jSaveMode.Overwrite elif mode == "ignore": jmode = jSaveMode.Ignore elif mode == "error": pass else: raise ValueError( "Only 'append', 'overwrite', 'ignore', and 'error' are acceptable save mode.") return jmode def saveAsTable(self, tableName, source=None, mode="append", **options): """Saves the contents of the DataFrame to a data source as a table. The data source is specified by the `source` and a set of `options`. If `source` is not specified, the default data source configured by spark.sql.sources.default will be used. Additionally, mode is used to specify the behavior of the saveAsTable operation when table already exists in the data source. There are four modes: * append: Contents of this DataFrame are expected to be appended to existing table. * overwrite: Data in the existing table is expected to be overwritten by the contents of \ this DataFrame. * error: An exception is expected to be thrown. * ignore: The save operation is expected to not save the contents of the DataFrame and \ to not change the existing table. """ if source is None: source = self.sql_ctx.getConf("spark.sql.sources.default", "org.apache.spark.sql.parquet") jmode = self._java_save_mode(mode) joptions = MapConverter().convert(options, self.sql_ctx._sc._gateway._gateway_client) self._jdf.saveAsTable(tableName, source, jmode, joptions) def save(self, path=None, source=None, mode="append", **options): """Saves the contents of the DataFrame to a data source. The data source is specified by the `source` and a set of `options`. If `source` is not specified, the default data source configured by spark.sql.sources.default will be used. Additionally, mode is used to specify the behavior of the save operation when data already exists in the data source. There are four modes: * append: Contents of this DataFrame are expected to be appended to existing data. * overwrite: Existing data is expected to be overwritten by the contents of this DataFrame. * error: An exception is expected to be thrown. * ignore: The save operation is expected to not save the contents of the DataFrame and \ to not change the existing data. """ if path is not None: options["path"] = path if source is None: source = self.sql_ctx.getConf("spark.sql.sources.default", "org.apache.spark.sql.parquet") jmode = self._java_save_mode(mode) joptions = MapConverter().convert(options, self._sc._gateway._gateway_client) self._jdf.save(source, jmode, joptions) def schema(self): """Returns the schema of this DataFrame (represented by a L{StructType}). >>> df.schema() StructType(List(StructField(age,IntegerType,true),StructField(name,StringType,true))) """ return _parse_datatype_json_string(self._jdf.schema().json()) def printSchema(self): """Prints out the schema in the tree format. >>> df.printSchema() root |-- age: integer (nullable = true) |-- name: string (nullable = true) """ print (self._jdf.schema().treeString()) def show(self): """ Print the first 20 rows. >>> df.show() age name 2 Alice 5 Bob >>> df age name 2 Alice 5 Bob """ print (self) def __repr__(self): return self._jdf.showString() 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 DataFrame, which supports features such as filter pushdown. >>> df.count() 2L """ return self._jdf.count() def collect(self): """Return a list that contains all of the rows. Each object in the list is a Row, the fields can be accessed as attributes. >>> df.collect() [Row(age=2, name=u'Alice'), Row(age=5, name=u'Bob')] """ with SCCallSiteSync(self._sc) as css: bytesInJava = self._jdf.javaToPython().collect().iterator() tempFile = NamedTemporaryFile(delete=False, dir=self._sc._temp_dir) tempFile.close() self._sc._writeToFile(bytesInJava, tempFile.name) # Read the data into Python and deserialize it: with open(tempFile.name, 'rb') as tempFile: rs = list(BatchedSerializer(PickleSerializer()).load_stream(tempFile)) os.unlink(tempFile.name) cls = _create_cls(self.schema()) return [cls(r) for r in rs] def limit(self, num): """Limit the result count to the number specified. >>> df.limit(1).collect() [Row(age=2, name=u'Alice')] >>> df.limit(0).collect() [] """ jdf = self._jdf.limit(num) return DataFrame(jdf, self.sql_ctx) def take(self, num): """Take the first num rows of the RDD. Each object in the list is a Row, the fields can be accessed as attributes. >>> df.take(2) [Row(age=2, name=u'Alice'), Row(age=5, name=u'Bob')] """ return self.limit(num).collect() def map(self, f): """ Return a new RDD by applying a function to each Row, it's a shorthand for df.rdd.map() >>> df.map(lambda p: p.name).collect() [u'Alice', u'Bob'] """ return self.rdd.map(f) def mapPartitions(self, f, preservesPartitioning=False): """ Return a new RDD by applying a function to each partition. >>> rdd = sc.parallelize([1, 2, 3, 4], 4) >>> def f(iterator): yield 1 >>> rdd.mapPartitions(f).sum() 4 """ return self.rdd.mapPartitions(f, preservesPartitioning) def cache(self): """ Persist with the default storage level (C{MEMORY_ONLY_SER}). """ self.is_cached = True self._jdf.cache() return self def persist(self, storageLevel=StorageLevel.MEMORY_ONLY_SER): """ Set the storage level to persist its values across operations after the first time it is computed. This can only be used to assign a new storage level if the RDD does not have a storage level set yet. If no storage level is specified defaults to (C{MEMORY_ONLY_SER}). """ self.is_cached = True javaStorageLevel = self._sc._getJavaStorageLevel(storageLevel) self._jdf.persist(javaStorageLevel) return self def unpersist(self, blocking=True): """ Mark it as non-persistent, and remove all blocks for it from memory and disk. """ self.is_cached = False self._jdf.unpersist(blocking) return self # def coalesce(self, numPartitions, shuffle=False): # rdd = self._jdf.coalesce(numPartitions, shuffle, None) # return DataFrame(rdd, self.sql_ctx) def repartition(self, numPartitions): """ Return a new :class:`DataFrame` that has exactly `numPartitions` partitions. """ rdd = self._jdf.repartition(numPartitions, None) return DataFrame(rdd, self.sql_ctx) def sample(self, withReplacement, fraction, seed=None): """ Return a sampled subset of this DataFrame. >>> df.sample(False, 0.5, 97).count() 1L """ assert fraction >= 0.0, "Negative fraction value: %s" % fraction seed = seed if seed is not None else random.randint(0, sys.maxint) rdd = self._jdf.sample(withReplacement, fraction, long(seed)) return DataFrame(rdd, self.sql_ctx) # def takeSample(self, withReplacement, num, seed=None): # """Return a fixed-size sampled subset of this DataFrame. # # >>> df = sqlCtx.inferSchema(rdd) # >>> df.takeSample(False, 2, 97) # [Row(field1=3, field2=u'row3'), Row(field1=1, field2=u'row1')] # """ # seed = seed if seed is not None else random.randint(0, sys.maxint) # with SCCallSiteSync(self.context) as css: # bytesInJava = self._jdf \ # .takeSampleToPython(withReplacement, num, long(seed)) \ # .iterator() # cls = _create_cls(self.schema()) # return map(cls, self._collect_iterator_through_file(bytesInJava)) @property def dtypes(self): """Return all column names and their data types as a list. >>> df.dtypes [('age', 'int'), ('name', 'string')] """ return [(str(f.name), f.dataType.simpleString()) for f in self.schema().fields] @property def columns(self): """ Return all column names as a list. >>> df.columns [u'age', u'name'] """ return [f.name for f in self.schema().fields] def join(self, other, joinExprs=None, joinType=None): """ Join with another DataFrame, using the given join expression. The following performs a full outer join between `df1` and `df2`:: :param other: Right side of the join :param joinExprs: Join expression :param joinType: One of `inner`, `outer`, `left_outer`, `right_outer`, `semijoin`. >>> df.join(df2, df.name == df2.name, 'outer').select(df.name, df2.height).collect() [Row(name=None, height=80), Row(name=u'Bob', height=85), Row(name=u'Alice', height=None)] """ if joinExprs is None: jdf = self._jdf.join(other._jdf) else: assert isinstance(joinExprs, Column), "joinExprs should be Column" if joinType is None: jdf = self._jdf.join(other._jdf, joinExprs._jc) else: assert isinstance(joinType, basestring), "joinType should be basestring" jdf = self._jdf.join(other._jdf, joinExprs._jc, joinType) return DataFrame(jdf, self.sql_ctx) def sort(self, *cols): """ Return a new :class:`DataFrame` sorted by the specified column. :param cols: The columns or expressions used for sorting >>> df.sort(df.age.desc()).collect() [Row(age=5, name=u'Bob'), Row(age=2, name=u'Alice')] >>> df.sortBy(df.age.desc()).collect() [Row(age=5, name=u'Bob'), Row(age=2, name=u'Alice')] """ if not cols: raise ValueError("should sort by at least one column") jcols = ListConverter().convert([_to_java_column(c) for c in cols], self._sc._gateway._gateway_client) jdf = self._jdf.sort(self._sc._jvm.PythonUtils.toSeq(jcols)) return DataFrame(jdf, self.sql_ctx) sortBy = sort def head(self, n=None): """ Return the first `n` rows or the first row if n is None. >>> df.head() Row(age=2, name=u'Alice') >>> df.head(1) [Row(age=2, name=u'Alice')] """ if n is None: rs = self.head(1) return rs[0] if rs else None return self.take(n) def first(self): """ Return the first row. >>> df.first() Row(age=2, name=u'Alice') """ return self.head() def __getitem__(self, item): """ Return the column by given name >>> df['age'].collect() [Row(age=2), Row(age=5)] >>> df[ ["name", "age"]].collect() [Row(name=u'Alice', age=2), Row(name=u'Bob', age=5)] >>> df[ df.age > 3 ].collect() [Row(age=5, name=u'Bob')] """ if isinstance(item, basestring): jc = self._jdf.apply(item) return Column(jc, self.sql_ctx) elif isinstance(item, Column): return self.filter(item) elif isinstance(item, list): return self.select(*item) else: raise IndexError("unexpected index: %s" % item) def __getattr__(self, name): """ Return the column by given name >>> df.age.collect() [Row(age=2), Row(age=5)] """ if name.startswith("__"): raise AttributeError(name) jc = self._jdf.apply(name) return Column(jc, self.sql_ctx) def select(self, *cols): """ Selecting a set of expressions. >>> df.select().collect() [Row(age=2, name=u'Alice'), Row(age=5, name=u'Bob')] >>> df.select('*').collect() [Row(age=2, name=u'Alice'), Row(age=5, name=u'Bob')] >>> df.select('name', 'age').collect() [Row(name=u'Alice', age=2), Row(name=u'Bob', age=5)] >>> df.select(df.name, (df.age + 10).alias('age')).collect() [Row(name=u'Alice', age=12), Row(name=u'Bob', age=15)] """ if not cols: cols = ["*"] jcols = ListConverter().convert([_to_java_column(c) for c in cols], self._sc._gateway._gateway_client) jdf = self._jdf.select(self.sql_ctx._sc._jvm.PythonUtils.toSeq(jcols)) return DataFrame(jdf, self.sql_ctx) def selectExpr(self, *expr): """ Selects a set of SQL expressions. This is a variant of `select` that accepts SQL expressions. >>> df.selectExpr("age * 2", "abs(age)").collect() [Row((age * 2)=4, Abs(age)=2), Row((age * 2)=10, Abs(age)=5)] """ jexpr = ListConverter().convert(expr, self._sc._gateway._gateway_client) jdf = self._jdf.selectExpr(self._sc._jvm.PythonUtils.toSeq(jexpr)) return DataFrame(jdf, self.sql_ctx) def filter(self, condition): """ Filtering rows using the given condition, which could be Column expression or string of SQL expression. where() is an alias for filter(). >>> df.filter(df.age > 3).collect() [Row(age=5, name=u'Bob')] >>> df.where(df.age == 2).collect() [Row(age=2, name=u'Alice')] >>> df.filter("age > 3").collect() [Row(age=5, name=u'Bob')] >>> df.where("age = 2").collect() [Row(age=2, name=u'Alice')] """ if isinstance(condition, basestring): jdf = self._jdf.filter(condition) elif isinstance(condition, Column): jdf = self._jdf.filter(condition._jc) else: raise TypeError("condition should be string or Column") return DataFrame(jdf, self.sql_ctx) where = filter def groupBy(self, *cols): """ Group the :class:`DataFrame` using the specified columns, so we can run aggregation on them. See :class:`GroupedData` for all the available aggregate functions. >>> df.groupBy().avg().collect() [Row(AVG(age#0)=3.5)] >>> df.groupBy('name').agg({'age': 'mean'}).collect() [Row(name=u'Bob', AVG(age#0)=5.0), Row(name=u'Alice', AVG(age#0)=2.0)] >>> df.groupBy(df.name).avg().collect() [Row(name=u'Bob', AVG(age#0)=5.0), Row(name=u'Alice', AVG(age#0)=2.0)] """ jcols = ListConverter().convert([_to_java_column(c) for c in cols], self._sc._gateway._gateway_client) jdf = self._jdf.groupBy(self.sql_ctx._sc._jvm.PythonUtils.toSeq(jcols)) return GroupedData(jdf, self.sql_ctx) def agg(self, *exprs): """ Aggregate on the entire :class:`DataFrame` without groups (shorthand for df.groupBy.agg()). >>> df.agg({"age": "max"}).collect() [Row(MAX(age#0)=5)] >>> from pyspark.sql import Dsl >>> df.agg(Dsl.min(df.age)).collect() [Row(MIN(age#0)=2)] """ return self.groupBy().agg(*exprs) def unionAll(self, other): """ Return a new DataFrame containing union of rows in this frame and another frame. This is equivalent to `UNION ALL` in SQL. """ return DataFrame(self._jdf.unionAll(other._jdf), self.sql_ctx) def intersect(self, other): """ Return a new :class:`DataFrame` containing rows only in both this frame and another frame. This is equivalent to `INTERSECT` in SQL. """ return DataFrame(self._jdf.intersect(other._jdf), self.sql_ctx) def subtract(self, other): """ Return a new :class:`DataFrame` containing rows in this frame but not in another frame. This is equivalent to `EXCEPT` in SQL. """ return DataFrame(getattr(self._jdf, "except")(other._jdf), self.sql_ctx) def addColumn(self, colName, col): """ Return a new :class:`DataFrame` by adding a column. >>> df.addColumn('age2', df.age + 2).collect() [Row(age=2, name=u'Alice', age2=4), Row(age=5, name=u'Bob', age2=7)] """ return self.select('*', col.alias(colName)) def renameColumn(self, existing, new): """ Rename an existing column to a new name >>> df.renameColumn('age', 'age2').collect() [Row(age2=2, name=u'Alice'), Row(age2=5, name=u'Bob')] """ cols = [Column(_to_java_column(c), self.sql_ctx).alias(new) if c == existing else c for c in self.columns] return self.select(*cols) def to_pandas(self): """ Collect all the rows and return a `pandas.DataFrame`. >>> df.to_pandas() # doctest: +SKIP age name 0 2 Alice 1 5 Bob """ import pandas as pd return pd.DataFrame.from_records(self.collect(), columns=self.columns) # Having SchemaRDD for backward compatibility (for docs) class SchemaRDD(DataFrame): """ SchemaRDD is deprecated, please use DataFrame """ def dfapi(f): def _api(self): name = f.__name__ jdf = getattr(self._jdf, name)() return DataFrame(jdf, self.sql_ctx) _api.__name__ = f.__name__ _api.__doc__ = f.__doc__ return _api class GroupedData(object): """ A set of methods for aggregations on a :class:`DataFrame`, created by DataFrame.groupBy(). """ def __init__(self, jdf, sql_ctx): self._jdf = jdf self.sql_ctx = sql_ctx def agg(self, *exprs): """ Compute aggregates by specifying a map from column name to aggregate methods. The available aggregate methods are `avg`, `max`, `min`, `sum`, `count`. :param exprs: list or aggregate columns or a map from column name to aggregate methods. >>> gdf = df.groupBy(df.name) >>> gdf.agg({"age": "max"}).collect() [Row(name=u'Bob', MAX(age#0)=5), Row(name=u'Alice', MAX(age#0)=2)] >>> from pyspark.sql import Dsl >>> gdf.agg(Dsl.min(df.age)).collect() [Row(MIN(age#0)=5), Row(MIN(age#0)=2)] """ assert exprs, "exprs should not be empty" if len(exprs) == 1 and isinstance(exprs[0], dict): jmap = MapConverter().convert(exprs[0], self.sql_ctx._sc._gateway._gateway_client) jdf = self._jdf.agg(jmap) else: # Columns assert all(isinstance(c, Column) for c in exprs), "all exprs should be Column" jcols = ListConverter().convert([c._jc for c in exprs[1:]], self.sql_ctx._sc._gateway._gateway_client) jdf = self._jdf.agg(exprs[0]._jc, self.sql_ctx._sc._jvm.PythonUtils.toSeq(jcols)) return DataFrame(jdf, self.sql_ctx) @dfapi def count(self): """ Count the number of rows for each group. >>> df.groupBy(df.age).count().collect() [Row(age=2, count=1), Row(age=5, count=1)] """ @dfapi def mean(self): """Compute the average value for each numeric columns for each group. This is an alias for `avg`.""" @dfapi def avg(self): """Compute the average value for each numeric columns for each group.""" @dfapi def max(self): """Compute the max value for each numeric columns for each group. """ @dfapi def min(self): """Compute the min value for each numeric column for each group.""" @dfapi def sum(self): """Compute the sum for each numeric columns for each group.""" def _create_column_from_literal(literal): sc = SparkContext._active_spark_context return sc._jvm.Dsl.lit(literal) def _create_column_from_name(name): sc = SparkContext._active_spark_context return sc._jvm.Dsl.col(name) def _to_java_column(col): if isinstance(col, Column): jcol = col._jc else: jcol = _create_column_from_name(col) return jcol def _unary_op(name, doc="unary operator"): """ Create a method for given unary operator """ def _(self): jc = getattr(self._jc, name)() return Column(jc, self.sql_ctx) _.__doc__ = doc return _ def _dsl_op(name, doc=''): def _(self): jc = getattr(self._sc._jvm.Dsl, name)(self._jc) return Column(jc, self.sql_ctx) _.__doc__ = doc return _ def _bin_op(name, doc="binary operator"): """ Create a method for given binary operator """ def _(self, other): jc = other._jc if isinstance(other, Column) else other njc = getattr(self._jc, name)(jc) return Column(njc, self.sql_ctx) _.__doc__ = doc return _ def _reverse_op(name, doc="binary operator"): """ Create a method for binary operator (this object is on right side) """ def _(self, other): jother = _create_column_from_literal(other) jc = getattr(jother, name)(self._jc) return Column(jc, self.sql_ctx) _.__doc__ = doc return _ class Column(DataFrame): """ A column in a DataFrame. `Column` instances can be created by:: # 1. Select a column out of a DataFrame df.colName df["colName"] # 2. Create from an expression df.colName + 1 1 / df.colName """ def __init__(self, jc, sql_ctx=None): self._jc = jc super(Column, self).__init__(jc, sql_ctx) # arithmetic operators __neg__ = _dsl_op("negate") __add__ = _bin_op("plus") __sub__ = _bin_op("minus") __mul__ = _bin_op("multiply") __div__ = _bin_op("divide") __mod__ = _bin_op("mod") __radd__ = _bin_op("plus") __rsub__ = _reverse_op("minus") __rmul__ = _bin_op("multiply") __rdiv__ = _reverse_op("divide") __rmod__ = _reverse_op("mod") # logistic operators __eq__ = _bin_op("equalTo") __ne__ = _bin_op("notEqual") __lt__ = _bin_op("lt") __le__ = _bin_op("leq") __ge__ = _bin_op("geq") __gt__ = _bin_op("gt") # `and`, `or`, `not` cannot be overloaded in Python, # so use bitwise operators as boolean operators __and__ = _bin_op('and') __or__ = _bin_op('or') __invert__ = _dsl_op('not') __rand__ = _bin_op("and") __ror__ = _bin_op("or") # container operators __contains__ = _bin_op("contains") __getitem__ = _bin_op("getItem") getField = _bin_op("getField", "An expression that gets a field by name in a StructField.") # string methods rlike = _bin_op("rlike") like = _bin_op("like") startswith = _bin_op("startsWith") endswith = _bin_op("endsWith") def substr(self, startPos, length): """ Return a Column which is a substring of the column :param startPos: start position (int or Column) :param length: length of the substring (int or Column) >>> df.name.substr(1, 3).collect() [Row(col=u'Ali'), Row(col=u'Bob')] """ if type(startPos) != type(length): raise TypeError("Can not mix the type") if isinstance(startPos, (int, long)): jc = self._jc.substr(startPos, length) elif isinstance(startPos, Column): jc = self._jc.substr(startPos._jc, length._jc) else: raise TypeError("Unexpected type: %s" % type(startPos)) return Column(jc, self.sql_ctx) __getslice__ = substr # order asc = _unary_op("asc") desc = _unary_op("desc") isNull = _unary_op("isNull", "True if the current expression is null.") isNotNull = _unary_op("isNotNull", "True if the current expression is not null.") def alias(self, alias): """Return a alias for this column >>> df.age.alias("age2").collect() [Row(age2=2), Row(age2=5)] """ return Column(getattr(self._jc, "as")(alias), self.sql_ctx) def cast(self, dataType): """ Convert the column into type `dataType` >>> df.select(df.age.cast("string").alias('ages')).collect() [Row(ages=u'2'), Row(ages=u'5')] >>> df.select(df.age.cast(StringType()).alias('ages')).collect() [Row(ages=u'2'), Row(ages=u'5')] """ if self.sql_ctx is None: sc = SparkContext._active_spark_context ssql_ctx = sc._jvm.SQLContext(sc._jsc.sc()) else: ssql_ctx = self.sql_ctx._ssql_ctx if isinstance(dataType, basestring): jc = self._jc.cast(dataType) elif isinstance(dataType, DataType): jdt = ssql_ctx.parseDataType(dataType.json()) jc = self._jc.cast(jdt) return Column(jc, self.sql_ctx) def __repr__(self): if self._jdf.isComputable(): return self._jdf.samples() else: return 'Column<%s>' % self._jdf.toString() def to_pandas(self): """ Return a pandas.Series from the column >>> df.age.to_pandas() # doctest: +SKIP 0 2 1 5 dtype: int64 """ import pandas as pd data = [c for c, in self.collect()] return pd.Series(data) def _aggregate_func(name, doc=""): """ Create a function for aggregator by name""" def _(col): sc = SparkContext._active_spark_context jc = getattr(sc._jvm.Dsl, name)(_to_java_column(col)) return Column(jc) _.__name__ = name _.__doc__ = doc return staticmethod(_) class UserDefinedFunction(object): def __init__(self, func, returnType): self.func = func self.returnType = returnType self._broadcast = None self._judf = self._create_judf() def _create_judf(self): f = self.func # put it in closure `func` func = lambda _, it: imap(lambda x: f(*x), it) ser = AutoBatchedSerializer(PickleSerializer()) command = (func, None, ser, ser) sc = SparkContext._active_spark_context pickled_command, broadcast_vars, env, includes = _prepare_for_python_RDD(sc, command, self) ssql_ctx = sc._jvm.SQLContext(sc._jsc.sc()) jdt = ssql_ctx.parseDataType(self.returnType.json()) judf = sc._jvm.UserDefinedPythonFunction(f.__name__, bytearray(pickled_command), env, includes, sc.pythonExec, broadcast_vars, sc._javaAccumulator, jdt) return judf def __del__(self): if self._broadcast is not None: self._broadcast.unpersist() self._broadcast = None def __call__(self, *cols): sc = SparkContext._active_spark_context jcols = ListConverter().convert([_to_java_column(c) for c in cols], sc._gateway._gateway_client) jc = self._judf.apply(sc._jvm.PythonUtils.toSeq(jcols)) return Column(jc) class Dsl(object): """ A collections of builtin aggregators """ DSLS = { 'lit': 'Creates a :class:`Column` of literal value.', 'col': 'Returns a :class:`Column` based on the given column name.', 'column': 'Returns a :class:`Column` based on the given column name.', 'upper': 'Converts a string expression to upper case.', 'lower': 'Converts a string expression to upper case.', 'sqrt': 'Computes the square root of the specified float value.', 'abs': 'Computes the absolutle value.', 'max': 'Aggregate function: returns the maximum value of the expression in a group.', 'min': 'Aggregate function: returns the minimum value of the expression in a group.', 'first': 'Aggregate function: returns the first value in a group.', 'last': 'Aggregate function: returns the last value in a group.', 'count': 'Aggregate function: returns the number of items in a group.', 'sum': 'Aggregate function: returns the sum of all values in the expression.', 'avg': 'Aggregate function: returns the average of the values in a group.', 'mean': 'Aggregate function: returns the average of the values in a group.', 'sumDistinct': 'Aggregate function: returns the sum of distinct values in the expression.', } for _name, _doc in DSLS.items(): locals()[_name] = _aggregate_func(_name, _doc) del _name, _doc @staticmethod def countDistinct(col, *cols): """ Return a new Column for distinct count of (col, *cols) >>> from pyspark.sql import Dsl >>> df.agg(Dsl.countDistinct(df.age, df.name).alias('c')).collect() [Row(c=2)] >>> df.agg(Dsl.countDistinct("age", "name").alias('c')).collect() [Row(c=2)] """ sc = SparkContext._active_spark_context jcols = ListConverter().convert([_to_java_column(c) for c in cols], sc._gateway._gateway_client) jc = sc._jvm.Dsl.countDistinct(_to_java_column(col), sc._jvm.PythonUtils.toSeq(jcols)) return Column(jc) @staticmethod def approxCountDistinct(col, rsd=None): """ Return a new Column for approxiate distinct count of (col, *cols) >>> from pyspark.sql import Dsl >>> df.agg(Dsl.approxCountDistinct(df.age).alias('c')).collect() [Row(c=2)] """ sc = SparkContext._active_spark_context if rsd is None: jc = sc._jvm.Dsl.approxCountDistinct(_to_java_column(col)) else: jc = sc._jvm.Dsl.approxCountDistinct(_to_java_column(col), rsd) return Column(jc) @staticmethod def udf(f, returnType=StringType()): """Create a user defined function (UDF) >>> slen = Dsl.udf(lambda s: len(s), IntegerType()) >>> df.select(slen(df.name).alias('slen')).collect() [Row(slen=5), Row(slen=3)] """ return UserDefinedFunction(f, returnType) def _test(): import doctest from pyspark.context import SparkContext from pyspark.sql import Row, SQLContext import pyspark.sql.dataframe globs = pyspark.sql.dataframe.__dict__.copy() sc = SparkContext('local[4]', 'PythonTest') globs['sc'] = sc globs['sqlCtx'] = sqlCtx = SQLContext(sc) rdd2 = sc.parallelize([Row(name='Alice', age=2), Row(name='Bob', age=5)]) rdd3 = sc.parallelize([Row(name='Tom', height=80), Row(name='Bob', height=85)]) globs['df'] = sqlCtx.inferSchema(rdd2) globs['df2'] = sqlCtx.inferSchema(rdd3) (failure_count, test_count) = doctest.testmod( pyspark.sql.dataframe, globs=globs, optionflags=doctest.ELLIPSIS | doctest.NORMALIZE_WHITESPACE) globs['sc'].stop() if failure_count: exit(-1) if __name__ == "__main__": _test()