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https://issues.apache.org/jira/browse/BEAM-7018?focusedWorklogId=277372&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-277372
]
ASF GitHub Bot logged work on BEAM-7018:
----------------------------------------
Author: ASF GitHub Bot
Created on: 16/Jul/19 09:39
Start Date: 16/Jul/19 09:39
Worklog Time Spent: 10m
Work Description: robertwb commented on pull request #8859: [BEAM-7018]
Added Regex transform for PythonSDK
URL: https://github.com/apache/beam/pull/8859#discussion_r303812627
##########
File path: sdks/python/apache_beam/transforms/util.py
##########
@@ -864,3 +867,225 @@ def add_window_info(element,
timestamp=DoFn.TimestampParam,
def expand(self, pcoll):
return pcoll | ParDo(self.add_window_info)
+
+
+class Regex(object):
+ """
+ PTransform to use Regular Expression to process the elements in a
+ PCollection.
+ """
+ @staticmethod
+ def _regex_compile(regex):
+ """Return re.compile if the regex has a string value"""
+ if isinstance(regex, str):
+ regex = re.compile(regex)
+ return regex
+
+ @staticmethod
+ @ptransform_fn
+ def _matches_all_object(pcoll, regex, group=None):
+ """
+ PTransform to find the matches as per the regex.
+ """
+ def _process(element):
+ m = regex.finditer(element)
+ results = list()
+ for _, match in enumerate(m, start=1):
+ results.append(match.group())
+ for groupNum in range(0, len(match.groups())):
+ results.append(match.group(groupNum + 1))
+ if results:
+ yield results
+ return pcoll | FlatMap(_process)
+
+ @staticmethod
+ @ptransform_fn
+ def _matches_kv_object(pcoll, regex, keyGroup, valueGroup):
+ """
+ PTransfrom to find the matches as per regex and return as a KV pair.
+ """
+ def _process(element):
+ match = regex.match(element)
+ if match:
+ yield (match.group(keyGroup), match.group(valueGroup))
+
+ return pcoll | FlatMap(_process)
+
+ @staticmethod
+ @typehints.with_input_types(str)
+ @typehints.with_output_types(str)
+ @ptransform_fn
+ def matches(pcoll, regex, group=None):
+ """
+ Returns the matches if the entire line matched the Regex. Returns the
+ entire line (group 0 by default). Group can be integer value and a string
+ value.
+
+ Args:
+ regex: the regular expression string or (re.compile) pattern.
+ group: (optional) name of the group, it can be integer or a string value.
+ """
+ regex = Regex._regex_compile(regex)
+ group = group or 0
+
+ def _process(element):
+ m = regex.match(element)
+ if m:
+ yield m.group(group)
+ return pcoll | FlatMap(_process)
+
+ @staticmethod
+ @typehints.with_input_types(str)
+ @typehints.with_output_types(str)
Review comment:
Regex._matches_all_object returns a PCollection of lists (of groups). I'm
not, however, sure that's what one wants.
It seems the most primitive operation would be to have a transform that
returns the (non-trivial) match objects themselves. Everything could then be
implemented on top of that (e.g. extracting various groups).
There's also a question of whether, when doing a "match all", a PCollection
of lists (on for each matching element) would be best to return, or a flattened
pcollection of all matches from all elements (less information, so I'd defer to
the former or let it be optional).
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Issue Time Tracking
-------------------
Worklog Id: (was: 277372)
> Regex transform for Python SDK
> ------------------------------
>
> Key: BEAM-7018
> URL: https://issues.apache.org/jira/browse/BEAM-7018
> Project: Beam
> Issue Type: New Feature
> Components: sdk-py-core
> Reporter: Rose Nguyen
> Assignee: Shehzaad Nakhoda
> Priority: Minor
> Time Spent: 4h 10m
> Remaining Estimate: 0h
>
> PTransorms to use Regular Expressions to process elements in a PCollection
> It should offer the same API as its Java counterpart:
> [https://github.com/apache/beam/blob/11a977b8b26eff2274d706541127c19dc93131a2/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Regex.java]
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