# apache_beam.transforms.combiners module¶

A library of basic combiner PTransform subclasses.

class apache_beam.transforms.combiners.Mean[source]

Bases: object

Combiners for computing arithmetic means of elements.

class Globally(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

combiners.Mean.Globally computes the arithmetic mean of the elements.

expand(pcoll)[source]
class PerKey(label=None)[source]

combiners.Mean.PerKey finds the means of the values for each key.

expand(pcoll)[source]
class apache_beam.transforms.combiners.Count[source]

Bases: object

Combiners for counting elements.

class Globally(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

combiners.Count.Globally counts the total number of elements.

expand(pcoll)[source]
class PerKey(label=None)[source]

combiners.Count.PerKey counts how many elements each unique key has.

expand(pcoll)[source]
class PerElement(label=None)[source]

combiners.Count.PerElement counts how many times each element occurs.

expand(pcoll)[source]
class apache_beam.transforms.combiners.Top[source]

Bases: object

Combiners for obtaining extremal elements.

class Of(n, **kwargs)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

Obtain a list of the compare-most N elements in a PCollection.

This transform will retrieve the n greatest elements in the PCollection to which it is applied, where “greatest” is determined by the comparator function supplied as the compare argument.

Creates a global Top operation.

The arguments ‘key’ and ‘reverse’ may be passed as keyword arguments, and have the same meaning as for Python’s sort functions.

Parameters: pcoll – PCollection to process. n – number of elements to extract from pcoll. **kwargs – may contain ‘key’ and/or ‘reverse’
default_label()[source]
expand(pcoll)[source]
class PerKey(n, **kwargs)[source]

Identifies the compare-most N elements associated with each key.

This transform will produce a PCollection mapping unique keys in the input PCollection to the n greatest elements with which they are associated, where “greatest” is determined by the comparator function supplied as the compare argument in the initializer.

Creates a per-key Top operation.

The arguments ‘key’ and ‘reverse’ may be passed as keyword arguments, and have the same meaning as for Python’s sort functions.

Parameters: pcoll – PCollection to process. n – number of elements to extract from pcoll. **kwargs – may contain ‘key’ and/or ‘reverse’
default_label()[source]
expand(pcoll)[source]

Expands the transform.

Raises TypeCheckError: If the output type of the input PCollection is not compatible with Tuple[A, B].

Parameters: pcoll – PCollection to process the PCollection containing the result.
static Largest(pcoll, n, has_defaults=True)[source]

Obtain a list of the greatest N elements in a PCollection.

static Smallest(pcoll, n, has_defaults=True)[source]

Obtain a list of the least N elements in a PCollection.

static LargestPerKey(pcoll, n)[source]

Identifies the N greatest elements associated with each key.

static SmallestPerKey(pcoll, n, reverse=True)[source]

Identifies the N least elements associated with each key.

class apache_beam.transforms.combiners.Sample[source]

Bases: object

Combiners for sampling n elements without replacement.

class FixedSizeGlobally(n)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

Sample n elements from the input PCollection without replacement.

expand(pcoll)[source]
display_data()[source]
default_label()[source]
class FixedSizePerKey(n)[source]

Sample n elements associated with each key without replacement.

expand(pcoll)[source]
display_data()[source]
default_label()[source]
class apache_beam.transforms.combiners.ToList(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

A global CombineFn that condenses a PCollection into a single list.

expand(pcoll)[source]
class apache_beam.transforms.combiners.ToDict(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

A global CombineFn that condenses a PCollection into a single dict.

PCollections should consist of 2-tuples, notionally (key, value) pairs. If multiple values are associated with the same key, only one of the values will be present in the resulting dict.

expand(pcoll)[source]
class apache_beam.transforms.combiners.ToSet(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

A global CombineFn that condenses a PCollection into a set.

expand(pcoll)[source]
class apache_beam.transforms.combiners.Latest[source]

Bases: object

Combiners for computing the latest element

class Globally(has_defaults=True)[source]

Bases: apache_beam.transforms.combiners.CombinerWithoutDefaults

Compute the element with the latest timestamp from a PCollection.

static add_timestamp(element, timestamp=TimestampParam)[source]
expand(pcoll)[source]
class PerKey(label=None)[source]

Compute elements with the latest timestamp for each key from a keyed PCollection

static add_timestamp(element, timestamp=TimestampParam)[source]
expand(pcoll)[source]