Source code for pyspark.sql.column

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import sys
import warnings
import json

if sys.version >= '3':
    basestring = str
    long = int

from pyspark import copy_func, since
from pyspark.context import SparkContext
from pyspark.rdd import ignore_unicode_prefix
from pyspark.sql.types import *

__all__ = ["Column"]


def _create_column_from_literal(literal):
    sc = SparkContext._active_spark_context
    return sc._jvm.functions.lit(literal)


def _create_column_from_name(name):
    sc = SparkContext._active_spark_context
    return sc._jvm.functions.col(name)


def _to_java_column(col):
    if isinstance(col, Column):
        jcol = col._jc
    else:
        jcol = _create_column_from_name(col)
    return jcol


def _to_seq(sc, cols, converter=None):
    """
    Convert a list of Column (or names) into a JVM Seq of Column.

    An optional `converter` could be used to convert items in `cols`
    into JVM Column objects.
    """
    if converter:
        cols = [converter(c) for c in cols]
    return sc._jvm.PythonUtils.toSeq(cols)


def _to_list(sc, cols, converter=None):
    """
    Convert a list of Column (or names) into a JVM (Scala) List of Column.

    An optional `converter` could be used to convert items in `cols`
    into JVM Column objects.
    """
    if converter:
        cols = [converter(c) for c in cols]
    return sc._jvm.PythonUtils.toList(cols)


def _unary_op(name, doc="unary operator"):
    """ Create a method for given unary operator """
    def _(self):
        jc = getattr(self._jc, name)()
        return Column(jc)
    _.__doc__ = doc
    return _


def _func_op(name, doc=''):
    def _(self):
        sc = SparkContext._active_spark_context
        jc = getattr(sc._jvm.functions, name)(self._jc)
        return Column(jc)
    _.__doc__ = doc
    return _


def _bin_func_op(name, reverse=False, doc="binary function"):
    def _(self, other):
        sc = SparkContext._active_spark_context
        fn = getattr(sc._jvm.functions, name)
        jc = other._jc if isinstance(other, Column) else _create_column_from_literal(other)
        njc = fn(self._jc, jc) if not reverse else fn(jc, self._jc)
        return Column(njc)
    _.__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)
    _.__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)
    _.__doc__ = doc
    return _


[docs]class Column(object): """ A column in a DataFrame. :class:`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 .. versionadded:: 1.3 """ def __init__(self, jc): self._jc = jc # arithmetic operators __neg__ = _func_op("negate") __add__ = _bin_op("plus") __sub__ = _bin_op("minus") __mul__ = _bin_op("multiply") __div__ = _bin_op("divide") __truediv__ = _bin_op("divide") __mod__ = _bin_op("mod") __radd__ = _bin_op("plus") __rsub__ = _reverse_op("minus") __rmul__ = _bin_op("multiply") __rdiv__ = _reverse_op("divide") __rtruediv__ = _reverse_op("divide") __rmod__ = _reverse_op("mod") __pow__ = _bin_func_op("pow") __rpow__ = _bin_func_op("pow", reverse=True) # 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__ = _func_op('not') __rand__ = _bin_op("and") __ror__ = _bin_op("or") # container operators def __contains__(self, item): raise ValueError("Cannot apply 'in' operator against a column: please use 'contains' " "in a string column or 'array_contains' function for an array column.") # bitwise operators bitwiseOR = _bin_op("bitwiseOR") bitwiseAND = _bin_op("bitwiseAND") bitwiseXOR = _bin_op("bitwiseXOR")
[docs] @since(1.3) def getItem(self, key): """ An expression that gets an item at position ``ordinal`` out of a list, or gets an item by key out of a dict. >>> df = sc.parallelize([([1, 2], {"key": "value"})]).toDF(["l", "d"]) >>> df.select(df.l.getItem(0), df.d.getItem("key")).show() +----+------+ |l[0]|d[key]| +----+------+ | 1| value| +----+------+ >>> df.select(df.l[0], df.d["key"]).show() +----+------+ |l[0]|d[key]| +----+------+ | 1| value| +----+------+ """ return self[key]
[docs] @since(1.3) def getField(self, name): """ An expression that gets a field by name in a StructField. >>> from pyspark.sql import Row >>> df = sc.parallelize([Row(r=Row(a=1, b="b"))]).toDF() >>> df.select(df.r.getField("b")).show() +---+ |r.b| +---+ | b| +---+ >>> df.select(df.r.a).show() +---+ |r.a| +---+ | 1| +---+ """ return self[name]
def __getattr__(self, item): if item.startswith("__"): raise AttributeError(item) return self.getField(item) def __getitem__(self, k): if isinstance(k, slice): if k.step is not None: raise ValueError("slice with step is not supported.") return self.substr(k.start, k.stop) else: return _bin_op("apply")(self, k) def __iter__(self): raise TypeError("Column is not iterable") # string methods _rlike_doc = """ Return a Boolean :class:`Column` based on a regex match. :param other: an extended regex expression >>> df.filter(df.name.rlike('ice$')).collect() [Row(age=2, name=u'Alice')] """ _like_doc = """ Return a Boolean :class:`Column` based on a SQL LIKE match. :param other: a SQL LIKE pattern See :func:`rlike` for a regex version >>> df.filter(df.name.like('Al%')).collect() [Row(age=2, name=u'Alice')] """ _startswith_doc = """ Return a Boolean :class:`Column` based on a string match. :param other: string at end of line (do not use a regex `^`) >>> df.filter(df.name.startswith('Al')).collect() [Row(age=2, name=u'Alice')] >>> df.filter(df.name.startswith('^Al')).collect() [] """ _endswith_doc = """ Return a Boolean :class:`Column` based on matching end of string. :param other: string at end of line (do not use a regex `$`) >>> df.filter(df.name.endswith('ice')).collect() [Row(age=2, name=u'Alice')] >>> df.filter(df.name.endswith('ice$')).collect() [] """ contains = _bin_op("contains") rlike = ignore_unicode_prefix(_bin_op("rlike", _rlike_doc)) like = ignore_unicode_prefix(_bin_op("like", _like_doc)) startswith = ignore_unicode_prefix(_bin_op("startsWith", _startswith_doc)) endswith = ignore_unicode_prefix(_bin_op("endsWith", _endswith_doc))
[docs] @ignore_unicode_prefix @since(1.3) def substr(self, startPos, length): """ Return a :class:`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.select(df.name.substr(1, 3).alias("col")).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)
[docs] @ignore_unicode_prefix @since(1.5) def isin(self, *cols): """ A boolean expression that is evaluated to true if the value of this expression is contained by the evaluated values of the arguments. >>> df[df.name.isin("Bob", "Mike")].collect() [Row(age=5, name=u'Bob')] >>> df[df.age.isin([1, 2, 3])].collect() [Row(age=2, name=u'Alice')] """ if len(cols) == 1 and isinstance(cols[0], (list, set)): cols = cols[0] cols = [c._jc if isinstance(c, Column) else _create_column_from_literal(c) for c in cols] sc = SparkContext._active_spark_context jc = getattr(self._jc, "isin")(_to_seq(sc, cols)) return Column(jc)
# order asc = _unary_op("asc", "Returns a sort expression based on the" " ascending order of the given column name.") desc = _unary_op("desc", "Returns a sort expression based on the" " descending order of the given column name.") _isNull_doc = """ True if the current expression is null. Often combined with :func:`DataFrame.filter` to select rows with null values. >>> from pyspark.sql import Row >>> df2 = sc.parallelize([Row(name=u'Tom', height=80), Row(name=u'Alice', height=None)]).toDF() >>> df2.filter(df2.height.isNull()).collect() [Row(height=None, name=u'Alice')] """ _isNotNull_doc = """ True if the current expression is null. Often combined with :func:`DataFrame.filter` to select rows with non-null values. >>> from pyspark.sql import Row >>> df2 = sc.parallelize([Row(name=u'Tom', height=80), Row(name=u'Alice', height=None)]).toDF() >>> df2.filter(df2.height.isNotNull()).collect() [Row(height=80, name=u'Tom')] """ isNull = ignore_unicode_prefix(_unary_op("isNull", _isNull_doc)) isNotNull = ignore_unicode_prefix(_unary_op("isNotNull", _isNotNull_doc))
[docs] @since(1.3) def alias(self, *alias, **kwargs): """ Returns this column aliased with a new name or names (in the case of expressions that return more than one column, such as explode). :param alias: strings of desired column names (collects all positional arguments passed) :param metadata: a dict of information to be stored in ``metadata`` attribute of the corresponding :class: `StructField` (optional, keyword only argument) .. versionchanged:: 2.2 Added optional ``metadata`` argument. >>> df.select(df.age.alias("age2")).collect() [Row(age2=2), Row(age2=5)] >>> df.select(df.age.alias("age3", metadata={'max': 99})).schema['age3'].metadata['max'] 99 """ metadata = kwargs.pop('metadata', None) assert not kwargs, 'Unexpected kwargs where passed: %s' % kwargs sc = SparkContext._active_spark_context if len(alias) == 1: if metadata: jmeta = sc._jvm.org.apache.spark.sql.types.Metadata.fromJson( json.dumps(metadata)) return Column(getattr(self._jc, "as")(alias[0], jmeta)) else: return Column(getattr(self._jc, "as")(alias[0])) else: if metadata: raise ValueError('metadata can only be provided for a single column') return Column(getattr(self._jc, "as")(_to_seq(sc, list(alias))))
name = copy_func(alias, sinceversion=2.0, doc=":func:`name` is an alias for :func:`alias`.")
[docs] @ignore_unicode_prefix @since(1.3) 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 isinstance(dataType, basestring): jc = self._jc.cast(dataType) elif isinstance(dataType, DataType): from pyspark.sql import SparkSession spark = SparkSession.builder.getOrCreate() jdt = spark._jsparkSession.parseDataType(dataType.json()) jc = self._jc.cast(jdt) else: raise TypeError("unexpected type: %s" % type(dataType)) return Column(jc)
astype = copy_func(cast, sinceversion=1.4, doc=":func:`astype` is an alias for :func:`cast`.")
[docs] @since(1.3) def between(self, lowerBound, upperBound): """ A boolean expression that is evaluated to true if the value of this expression is between the given columns. >>> df.select(df.name, df.age.between(2, 4)).show() +-----+---------------------------+ | name|((age >= 2) AND (age <= 4))| +-----+---------------------------+ |Alice| true| | Bob| false| +-----+---------------------------+ """ return (self >= lowerBound) & (self <= upperBound)
[docs] @since(1.4) def when(self, condition, value): """ Evaluates a list of conditions and returns one of multiple possible result expressions. If :func:`Column.otherwise` is not invoked, None is returned for unmatched conditions. See :func:`pyspark.sql.functions.when` for example usage. :param condition: a boolean :class:`Column` expression. :param value: a literal value, or a :class:`Column` expression. >>> from pyspark.sql import functions as F >>> df.select(df.name, F.when(df.age > 4, 1).when(df.age < 3, -1).otherwise(0)).show() +-----+------------------------------------------------------------+ | name|CASE WHEN (age > 4) THEN 1 WHEN (age < 3) THEN -1 ELSE 0 END| +-----+------------------------------------------------------------+ |Alice| -1| | Bob| 1| +-----+------------------------------------------------------------+ """ if not isinstance(condition, Column): raise TypeError("condition should be a Column") v = value._jc if isinstance(value, Column) else value jc = self._jc.when(condition._jc, v) return Column(jc)
[docs] @since(1.4) def otherwise(self, value): """ Evaluates a list of conditions and returns one of multiple possible result expressions. If :func:`Column.otherwise` is not invoked, None is returned for unmatched conditions. See :func:`pyspark.sql.functions.when` for example usage. :param value: a literal value, or a :class:`Column` expression. >>> from pyspark.sql import functions as F >>> df.select(df.name, F.when(df.age > 3, 1).otherwise(0)).show() +-----+-------------------------------------+ | name|CASE WHEN (age > 3) THEN 1 ELSE 0 END| +-----+-------------------------------------+ |Alice| 0| | Bob| 1| +-----+-------------------------------------+ """ v = value._jc if isinstance(value, Column) else value jc = self._jc.otherwise(v) return Column(jc)
[docs] @since(1.4) def over(self, window): """ Define a windowing column. :param window: a :class:`WindowSpec` :return: a Column >>> from pyspark.sql import Window >>> window = Window.partitionBy("name").orderBy("age").rowsBetween(-1, 1) >>> from pyspark.sql.functions import rank, min >>> # df.select(rank().over(window), min('age').over(window)) """ from pyspark.sql.window import WindowSpec if not isinstance(window, WindowSpec): raise TypeError("window should be WindowSpec") jc = self._jc.over(window._jspec) return Column(jc)
def __nonzero__(self): raise ValueError("Cannot convert column into bool: please use '&' for 'and', '|' for 'or', " "'~' for 'not' when building DataFrame boolean expressions.") __bool__ = __nonzero__ def __repr__(self): return 'Column<%s>' % self._jc.toString().encode('utf8')
def _test(): import doctest from pyspark.sql import SparkSession import pyspark.sql.column globs = pyspark.sql.column.__dict__.copy() spark = SparkSession.builder\ .master("local[4]")\ .appName("sql.column tests")\ .getOrCreate() sc = spark.sparkContext globs['sc'] = sc globs['df'] = sc.parallelize([(2, 'Alice'), (5, 'Bob')]) \ .toDF(StructType([StructField('age', IntegerType()), StructField('name', StringType())])) (failure_count, test_count) = doctest.testmod( pyspark.sql.column, globs=globs, optionflags=doctest.ELLIPSIS | doctest.NORMALIZE_WHITESPACE | doctest.REPORT_NDIFF) spark.stop() if failure_count: exit(-1) if __name__ == "__main__": _test()