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https://issues.apache.org/jira/browse/BEAM-5431?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stephan Hoyer updated BEAM-5431:
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Resolution: Fixed
Status: Resolved (was: Open)
beam.MapTuple and beam.FlatMapTuple implement this funtionality.
> StarMap transform for Python SDK
> --------------------------------
>
> Key: BEAM-5431
> URL: https://issues.apache.org/jira/browse/BEAM-5431
> Project: Beam
> Issue Type: New Feature
> Components: sdk-py-core
> Reporter: Stephan Hoyer
> Priority: P3
>
> I'd like to propose a new high-level transform "StarMap" for the Python SDK.
> The transform would be syntactic sugar for ParDo like Map, but would would
> automatically unpack arguments like
> [itertools.starmap|https://docs.python.org/3/library/itertools.html#itertools.starmap]
> from Python's standard library.
> The use-case is to handle applying functions to tuples of arguments, which is
> a common pattern when using Beam's combine and group-by transforms. Right
> now, it's common to write functions with manual unpacking, e.g.,
> {code:java}
> def my_func(inputs):
> key, value = inputs
> ...
> beam.Map(my_func) {code}
> StarMap offers a much more readable alternative:
> {code:java}
> def my_func(key, value):
> ...
> beam.StarMap(my_func){code}
>
> The need for StarMap is especially pressing with the advent of Python 3
> support and the eventual wind-down of Python 2. Currently, it's common to
> achieve this pattern using unpacking in a function definition, e.g.,
> beam.Map(lambda (k, v): my_func(k, v)), but this is invalid syntax in Python
> 3. My internal search of Google's codebase turns up quite a few matches for
> "beam\.Map(lambda\ (", none of which would work on Python 3.
>
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