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Diffstat (limited to 'python/pyspark/sql/column.py')
-rw-r--r-- | python/pyspark/sql/column.py | 360 |
1 files changed, 360 insertions, 0 deletions
diff --git a/python/pyspark/sql/column.py b/python/pyspark/sql/column.py new file mode 100644 index 0000000000..fc7ad674da --- /dev/null +++ b/python/pyspark/sql/column.py @@ -0,0 +1,360 @@ +# +# 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 + +if sys.version >= '3': + basestring = str + long = int + +from pyspark.context import SparkContext +from pyspark.rdd import ignore_unicode_prefix +from pyspark.sql.types import * + +__all__ = ["DataFrame", "Column", "SchemaRDD", "DataFrameNaFunctions", + "DataFrameStatFunctions"] + + +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 _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_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 _ + + +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 + """ + + 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") + + # 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 + __contains__ = _bin_op("contains") + __getitem__ = _bin_op("apply") + + # bitwise operators + bitwiseOR = _bin_op("bitwiseOR") + bitwiseAND = _bin_op("bitwiseAND") + bitwiseXOR = _bin_op("bitwiseXOR") + + 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] + + 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) + + # string methods + rlike = _bin_op("rlike") + like = _bin_op("like") + startswith = _bin_op("startsWith") + endswith = _bin_op("endsWith") + + @ignore_unicode_prefix + 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) + + __getslice__ = substr + + @ignore_unicode_prefix + def inSet(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.inSet("Bob", "Mike")].collect() + [Row(age=5, name=u'Bob')] + >>> df[df.age.inSet([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, "in")(_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 = _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): + """Returns this column aliased with a new name or names (in the case of expressions that + return more than one column, such as explode). + + >>> df.select(df.age.alias("age2")).collect() + [Row(age2=2), Row(age2=5)] + """ + + if len(alias) == 1: + return Column(getattr(self._jc, "as")(alias[0])) + else: + sc = SparkContext._active_spark_context + return Column(getattr(self._jc, "as")(_to_seq(sc, list(alias)))) + + @ignore_unicode_prefix + 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): + sc = SparkContext._active_spark_context + ssql_ctx = sc._jvm.SQLContext(sc._jsc.sc()) + jdt = ssql_ctx.parseDataType(dataType.json()) + jc = self._jc.cast(jdt) + else: + raise TypeError("unexpected type: %s" % type(dataType)) + return Column(jc) + + @ignore_unicode_prefix + def between(self, lowerBound, upperBound): + """ A boolean expression that is evaluated to true if the value of this + expression is between the given columns. + """ + return (self >= lowerBound) & (self <= upperBound) + + @ignore_unicode_prefix + 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. + + """ + sc = SparkContext._active_spark_context + if not isinstance(condition, Column): + raise TypeError("condition should be a Column") + v = value._jc if isinstance(value, Column) else value + jc = sc._jvm.functions.when(condition._jc, v) + return Column(jc) + + @ignore_unicode_prefix + 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. + """ + v = value._jc if isinstance(value, Column) else value + jc = self._jc.otherwise(value) + return Column(jc) + + def __repr__(self): + return 'Column<%s>' % self._jc.toString().encode('utf8') + + +def _test(): + import doctest + from pyspark.context import SparkContext + from pyspark.sql import SQLContext + import pyspark.sql.column + globs = pyspark.sql.column.__dict__.copy() + sc = SparkContext('local[4]', 'PythonTest') + globs['sc'] = sc + globs['sqlContext'] = SQLContext(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) + globs['sc'].stop() + if failure_count: + exit(-1) + + +if __name__ == "__main__": + _test() |