Add new section to lesson 4

[albhasan]

Closes #118

This PR:

• adds a new section about removing columns and rows from data frames.
• adds an example and a reference to the functions typeof and na.omit.

These changes addresses the issues raised by @sstevens2, regarding objectives missed by lesson 4.

[github-actions]

Thank you!

Thank you for your pull request 😃

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Rendered Changes

🔍 Inspect the changes: https://github.com/datacarpentry/r-intro-geospatial/compare/md-outputs..md-outputs-PR-149

The following changes were observed in the rendered markdown documents:

 04-data-structures-part2.md | 136 +++++++++++++++++++++++++++++++++++++++++++-
 md5sum.txt                  |   2 +-
 2 files changed, 136 insertions(+), 2 deletions(-)

What does this mean?

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⏱️ Updated at 2026-02-02 17:15:28 +0000

[albhasan]

Can I close this PR, @mikemahoney218?

[mikemahoney218]

Sorry, I've been particularly busy recently and haven't had a chance to look this over -- I'll try to check it out this week (unless @likeajumprope gets to it first of course!)

[kristi-sara]

@albhasan and @mikemahoney218 should ^ be merged?

[albhasan]

Hey @kristi-sara,

I wrote the PR, so I guess it should. However, it would be better if a maintainer checks it first.

Bests,

[albhasan]

@sstevens2 I think this is ready. Please take a look and if it is actually ready, can you please merge it?

[sstevens2]

This looks really good to me! I added a couple of small changes. My earlier changes removed the mention of "vector recycling" so the definition didn't have any context around it. I added back in the term with the short definition and then made the longer definition a spoiler since it isn't as vital to the lesson with the short description.

@albhasan I'm not a maintainer on this lesson, only an active instructor of it. I can't merge the PR.

[albhasan]

@sstevens2 Thanks for your contributions!

I'm gonna ask a mantainer for a review and commit. Thanks again!

[albhasan]

Good morning,

I think this PR has been open for too long. Can a maintainer please review it and, given the case, close it?

@datacarpentry/r-intro-geospatial-maintainers
@kristi-sara
@likeajumprope
@coopermkr
@mikemahoney218

Bests,

[coopermkr]

This addition looks great! There are a few minor spelling mistakes that I left comments on. Once those are fixed this is approved for merging.

[albhasan]

Thanks @coopermkr - I fixed the typos! I'm going to wait a couple of days just in case we receive more suggestions, and then I'm going to merge and close this PR.