def create_groups(group_ids, corpus, word, ignore_corpus, ignore_word):
"""Generate groups given the input PCollections."""
def attach_corpus_fn(group, corpus, ignore):
selected = None
len_corpus = len(corpus)
while not selected:
c = corpus[randrange(0, len_corpus - 1)].values()[0]
if c != ignore:
selected = c
yield (group, selected)
def attach_word_fn(group, words, ignore):
selected = None
len_words = len(words)
while not selected:
c = words[randrange(0, len_words - 1)].values()[0]
if c != ignore:
selected = c
yield group + (selected, )
return (group_ids
| df.FlatMap('attach corpus', attach_corpus_fn, AsList(corpus),
AsSingleton(ignore_corpus))
| df.FlatMap('attach word', attach_word_fn, AsIter(word),
AsSingleton(ignore_word)))
def apply(self, pcoll):
sink_coll = pcoll.pipeline | core.Create('create_sink_collection',
[self.sink])
init_result_coll = sink_coll | core.Map(
'initialize_write', lambda sink: sink.initialize_write())
write_result_coll = pcoll | core.ParDo(
'write_bundles', _WriteBundleDoFn(), AsSingleton(sink_coll),
AsSingleton(init_result_coll))
return sink_coll | core.FlatMap(
'finalize_write', lambda sink, init_result, write_results: sink.
finalize_write(init_result, write_results),
AsSingleton(init_result_coll), AsIter(write_result_coll))
def apply(self, pcoll):
sink_coll = pcoll.pipeline | core.Create('create_sink_collection',
[self.sink])
init_result_coll = sink_coll | core.Map(
'initialize_write', lambda sink: sink.initialize_write())
write_result_coll = pcoll | core.ParDo(
'write_bundles', _WriteBundleDoFn(), AsSingleton(sink_coll),
AsSingleton(init_result_coll))
return sink_coll | core.FlatMap(
'finalize_write', lambda sink, init_result, write_results:
(window.TimestampedValue(v, window.MAX_TIMESTAMP)
for v in sink.finalize_write(init_result, write_results) or
()), AsSingleton(init_result_coll), AsIter(write_result_coll))
def test_as_singleton_with_different_defaults_without_unique_labels(self):
# This should fail as AsSingleton with distinct default values should create
# distinct PCollectionViews with the same full_label.
a_list = [2]
pipeline = Pipeline('DirectPipelineRunner')
main_input = pipeline | Create('main input', [1])
side_list = pipeline | Create('side list', a_list)
with self.assertRaises(RuntimeError) as e:
_ = main_input | FlatMap('test', lambda x, s1, s2: [[x, s1, s2]],
AsSingleton(side_list),
AsSingleton(side_list, default_value=3))
self.assertTrue(
e.exception.message.startswith(
'Transform "ViewAsSingleton(side list.None)" does not have a '
'stable unique label.'))
def test_multi_valued_singleton_side_input(self):
pipeline = Pipeline('DirectPipelineRunner')
pcol = pipeline | Create('start', [1, 2])
side = pipeline | Create('side', [3, 4]) # 2 values in side input.
pcol | FlatMap('compute', lambda x, s: [x * s], AsSingleton(side))
with self.assertRaises(ValueError) as e:
pipeline.run()
def test_default_value_singleton_side_input(self):
pipeline = Pipeline('DirectPipelineRunner')
pcol = pipeline | Create('start', [1, 2])
side = pipeline | Create('side', []) # 0 values in side input.
result = (pcol | FlatMap('compute', lambda x, s: [x * s],
AsSingleton(side, 10)))
assert_that(result, equal_to([10, 20]))
pipeline.run()
def test_par_do_with_side_input_as_arg(self):
pipeline = Pipeline('DirectPipelineRunner')
words_list = ['aa', 'bb', 'cc']
words = pipeline | Create('SomeWords', words_list)
prefix = pipeline | Create('SomeString', ['xyz']) # side in
suffix = 'zyx'
result = words | FlatMap(
'DecorateWords', lambda x, pfx, sfx: ['%s-%s-%s' % (pfx, x, sfx)],
AsSingleton(prefix), suffix)
assert_that(result, equal_to(['xyz-%s-zyx' % x for x in words_list]))
pipeline.run()
def test_as_singleton_with_different_defaults_with_unique_labels(self):
a_list = []
pipeline = Pipeline('DirectPipelineRunner')
main_input = pipeline | Create('main input', [1])
side_list = pipeline | Create('side list', a_list)
results = main_input | FlatMap(
'test', lambda x, s1, s2: [[x, s1, s2]],
AsSingleton('si1', side_list, default_value=2),
AsSingleton('si2', side_list, default_value=3))
def matcher(expected_elem, expected_singleton1, expected_singleton2):
def match(actual):
[[actual_elem, actual_singleton1, actual_singleton2]] = actual
equal_to([expected_elem])([actual_elem])
equal_to([expected_singleton1])([actual_singleton1])
equal_to([expected_singleton2])([actual_singleton2])
return match
assert_that(results, matcher(1, 2, 3))
pipeline.run()
def test_empty_singleton_side_input(self):
pipeline = Pipeline('DirectPipelineRunner')
pcol = pipeline | Create('start', [1, 2])
side = pipeline | Create('side', []) # Empty side input.
def my_fn(k, s):
v = ('empty' if isinstance(s, EmptySideInput) else 'full')
return [(k, v)]
result = pcol | FlatMap('compute', my_fn, AsSingleton(side))
assert_that(result, equal_to([(1, 'empty'), (2, 'empty')]))
pipeline.run()
def test_as_singleton_without_unique_labels(self):
# This should succeed as calling AsSingleton on the same PCollection twice
# with the same defaults will return the same PCollectionView.
a_list = [2]
pipeline = Pipeline('DirectPipelineRunner')
main_input = pipeline | Create('main input', [1])
side_list = pipeline | Create('side list', a_list)
results = main_input | FlatMap('test', lambda x, s1, s2: [[x, s1, s2]],
AsSingleton(side_list),
AsSingleton(side_list))
def matcher(expected_elem, expected_singleton):
def match(actual):
[[actual_elem, actual_singleton1, actual_singleton2]] = actual
equal_to([expected_elem])([actual_elem])
equal_to([expected_singleton])([actual_singleton1])
equal_to([expected_singleton])([actual_singleton2])
return match
assert_that(results, matcher(1, 2))
pipeline.run()
def test_pcollectionview_not_recreated(self):
pipeline = Pipeline('DirectPipelineRunner')
value = pipeline | Create('create1', [1, 2, 3])
value2 = pipeline | Create('create2', [(1, 1), (2, 2), (3, 3)])
self.assertEqual(AsSingleton(value), AsSingleton(value))
self.assertEqual(AsSingleton('new', value, default_value=1),
AsSingleton('new', value, default_value=1))
self.assertNotEqual(AsSingleton(value),
AsSingleton('new', value, default_value=1))
self.assertEqual(AsIter(value), AsIter(value))
self.assertEqual(AsList(value), AsList(value))
self.assertEqual(AsDict(value2), AsDict(value2))
self.assertNotEqual(AsSingleton(value), AsSingleton(value2))
self.assertNotEqual(AsIter(value), AsIter(value2))
self.assertNotEqual(AsList(value), AsList(value2))
self.assertNotEqual(AsDict(value), AsDict(value2))
def test_par_do_with_do_fn_object(self):
class SomeDoFn(DoFn):
"""A custom DoFn for a FlatMap transform."""
def process(self, context, prefix, suffix):
return ['%s-%s-%s' % (prefix, context.element, suffix)]
pipeline = Pipeline('DirectPipelineRunner')
words_list = ['aa', 'bb', 'cc']
words = pipeline | Create('SomeWords', words_list)
prefix = 'zyx'
suffix = pipeline | Create('SomeString', ['xyz']) # side in
result = words | ParDo('DecorateWordsDoFn',
SomeDoFn(),
prefix,
suffix=AsSingleton(suffix))
assert_that(result, equal_to(['zyx-%s-xyz' % x for x in words_list]))
pipeline.run()
def filter_cold_days(input_data, month_filter):
"""Workflow computing rows in a specific month with low temperatures.
Args:
input_data: a PCollection of dictionaries representing table rows. Each
dictionary must have the keys ['year', 'month', 'day', and 'mean_temp'].
month_filter: an int representing the month for which colder-than-average
days should be returned.
Returns:
A PCollection of dictionaries with the same keys described above. Each
row represents a day in the specified month where temperatures were
colder than the global mean temperature in the entire dataset.
"""
# Project to only the desired fields from a complete input row.
# E.g., SELECT f1, f2, f3, ... FROM InputTable.
projection_fields = ['year', 'month', 'day', 'mean_temp']
fields_of_interest = (
input_data
| df.Map('projected',
lambda row: {f: row[f]
for f in projection_fields}))
# Compute the global mean temperature.
global_mean = AsSingleton(
fields_of_interest
| df.Map('extract mean', lambda row: row['mean_temp'])
| df.combiners.Mean.Globally('global mean'))
# Filter to the rows representing days in the month of interest
# in which the mean daily temperature is below the global mean.
return (
fields_of_interest
| df.Filter('desired month', lambda row: row['month'] == month_filter)
| df.Filter('below mean', lambda row, mean: row['mean_temp'] < mean,
global_mean))
# Compute a mapping from each word to its document frequency.
# A word's document frequency in a corpus is the number of
# documents in which the word appears divided by the total
# number of documents in the corpus.
#
# This calculation uses a side input, a Dataflow-computed auxiliary value
# presented to each invocation of our MapFn lambda. The second argument to
# the lambda (called total---note that we are unpacking the first argument)
# receives the value we listed after the lambda in Map(). Additional side
# inputs (and ordinary Python values, too) can be provided to MapFns and
# DoFns in this way.
word_to_df = (word_to_doc_count
| df.Map(
'compute doc frequencies', lambda
(word, count), total: (word, float(count) / total),
AsSingleton(total_documents)))
# Join the term frequency and document frequency collections,
# each keyed on the word.
word_to_uri_and_tf_and_df = ({
'tf': word_to_uri_and_tf,
'df': word_to_df
}
|
df.CoGroupByKey('cogroup words by tf-df'))
# Compute a mapping from each word to a (URI, TF-IDF) score for each URI.
# There are a variety of definitions of TF-IDF
# ("term frequency - inverse document frequency") score; here we use a
# basic version that is the term frequency divided by the log of the
# document frequency.
