Fixing unintentional variable overloading

[zjost]

Description

In the recommender example, the for loop uses i for enumeration, but then i is also used within the loop for list comprehensions, which breaks their utility. Instead of being an integer, i becomes an mx.nd.array

resolves #14439

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
• For new C++ functions in header files, their functionalities and arguments are documented.
• For new examples, README.md is added to explain the what the example does, the source of the dataset, expected performance on test set and reference to the original paper if applicable
• Check the API doc at http://mxnet-ci-doc.s3-accelerate.dualstack.amazonaws.com/PR-$PR_ID/$BUILD_ID/index.html
• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• Changed from symbol i to idx in loop within matrix_fact.evaluate_network
• Changed from symbol i to idx in loop within matrix_fact.train

Comments

[szha]

thanks for the fix and welcome to mxnet. would you mind also adding an entry for yourself in https://github.com/apache/incubator-mxnet/blob/master/CONTRIBUTORS.md#list-of-contributors

[zjost]

Done, thanks!

[karan6181]

@mxnet-label-bot add [Example, Bug, Python, pr-awaiting-testing]

[karan6181]

@zjost Thank you for your contribution!

Could you please look into the CI test failure? Thanks!

[zjost]

Looks like something related to a clojure artifact. This should have nothing to do with my changes.

[zachgk]

@zjost Cool trick: If you edit the PR description and add resolves #14439, then it will automatically resolve the issue when the PR is merged (https://help.github.com/en/articles/closing-issues-using-keywords). Otherwise, it is good to at least mention the issue from the PR.

Your PR is breaking on the clojure test due to an unrelated issue (#14448). You should rebase your commit onto master (git pull --rebase) so the fix to that issue is applied to your commit. It should pass the CI after that

[zjost]

The command '/bin/sh -c /work/ubuntu_publish.sh' returned a non-zero code: 100

[anirudh2290]

@zjost you can push an empty commit to retrigger the test. also can you rebase the latest master onto your branch.

[zjost]

If the code leading to the test failures is already in master, what's the harm of merging my rather innocuous changes to the example? Presumably the code I'm needing to rebase against is failing the same tests.

[zjost]

Sweet, thanks!

[szha]

@zjost thanks for the patch!