[jira] [Created] (SYSTEMML-676) Improve PyDML Slicing

["Mike Dusenberry (JIRA)" <ji...@apache.org>]

Mike Dusenberry created SYSTEMML-676:
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             Summary: Improve PyDML Slicing
                 Key: SYSTEMML-676
                 URL: https://issues.apache.org/jira/browse/SYSTEMML-676
             Project: SystemML
          Issue Type: Improvement
            Reporter: Mike Dusenberry


Currently, slicing correctly uses inclusive lower and exclusive upper bounds. However, a really useful piece of slicing syntax we are currently missing from PyDML is the ability to have implicit lower or upper bounds, i.e., {{X[ :3, ]}} should return all rows up to (but not including) 3. This means that the implicit lower bound is 0. Similarly, {{X[ 2:, ]}} should return all rows starting at row 2 (0-based), which implies that the upper bound is equal to the number of rows of {{X}}.

We should update the grammar to allow these cases, row both row and column slicing.  More generally, {{X[ :,: ]}}, should also be valid, regardless if it is useful.



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