[
https://issues.apache.org/jira/browse/BEAM-7018?focusedWorklogId=278974&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-278974
]
ASF GitHub Bot logged work on BEAM-7018:
----------------------------------------
Author: ASF GitHub Bot
Created on: 18/Jul/19 13:08
Start Date: 18/Jul/19 13:08
Worklog Time Spent: 10m
Work Description: mszb commented on pull request #8859: [BEAM-7018] Added
Regex transform for PythonSDK
URL: https://github.com/apache/beam/pull/8859#discussion_r304906778
##########
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:
As per the java implementation, matches_kv return the list of KV (of
groups).
https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Regex.java#L558
I've updated the code little bit and found we no longer require
`Regex._matches_all_object` as a separate private method so I moved the
functionality in the `Regex.matches_kv` and removed the
`Regex._matches_all_object` method.
(Previously I was using `Regex._matches_all_object` for both (`matches_kv` &
`find_kv`), and now after the changes, I am using `re.match` for `matches_kv`
and `re.finditer` for `find_kv`.)
And the third point regarding the return of the "match all". I think (the
first approach you mentioned) PCollection of lists (containing the matching
element of each item) is more relevant. Because (as in the java api) "match
all" applies to a single item of a collection, not to the entire collection.
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Issue Time Tracking
-------------------
Worklog Id: (was: 278974)
Time Spent: 7h (was: 6h 50m)
> 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: 7h
> 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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