Add wiki documentation for frequency_table, frequency_table_with_null, entropy, and average_entropy

[Copilot]

Four aggregation functions implemented in Modus.cpp have been undocumented since v14.4.0. This PR adds/updates their wiki pages in wiki/.

Changes

• wiki/frequency_table.md — Updated stub with full description: per-partition output format ("value1: count1; value2: count2; ..."), null-exclusion behavior, correct value type coverage (any scalar, not just string), and cross-reference to frequency_table_with_null
• wiki/frequency_table_with_null.md — New page; same as frequency_table but null values in a are counted and emitted as <null>: count
• wiki/entropy.md — New page; documents total Shannon entropy: entropy(a) = −∑ nᵢ · log₂(nᵢ/N) = N · H(a)
• wiki/average_entropy.md — New page; documents per-element Shannon entropy: average_entropy(a) = H(a) = entropy(a) / N = −∑ pᵢ · log₂(pᵢ)

Key distinction between entropy functions

Function	Returns	Formula
entropy(a, rel)	Total entropy per partition	−∑ nᵢ · log₂(nᵢ/N)
average_entropy(a, rel)	Shannon entropy per partition	−∑ pᵢ · log₂(pᵢ)

All pages follow existing wiki conventions (syntax / definition / description / applies-to / conditions / since version / example / see-also).

Note for maintainers: Files in wiki/ should be pushed to the GeoDMS wiki repository to publish them.

[MaartenHilferink]

@copilot ... how do I get these new pages into the repository's wiki?

[Copilot]

@copilot ... how do I get these new pages into the repository's wiki?

The wiki pages are in the wiki/ directory of this PR branch. GitHub wikis are stored in a separate git repository (https://github.com/ObjectVision/GeoDMS.wiki.git). To publish them, run the following commands after merging this PR:

git clone https://github.com/ObjectVision/GeoDMS.wiki.git
cd GeoDMS.wiki

# Copy the new/updated files from the main repo
cp /path/to/GeoDMS/wiki/frequency_table.md .
cp /path/to/GeoDMS/wiki/frequency_table_with_null.md .
cp /path/to/GeoDMS/wiki/entropy.md .
cp /path/to/GeoDMS/wiki/average_entropy.md .

git add frequency_table.md frequency_table_with_null.md entropy.md average_entropy.md
git commit -m "Add documentation for frequency_table, frequency_table_with_null, entropy, and average_entropy"
git push origin master

Alternatively, you can edit the pages directly on GitHub at https://github.com/ObjectVision/GeoDMS/wiki — create new pages for entropy, average_entropy, and frequency_table_with_null, and edit the existing frequency_table page by copying the content from the respective .md files in this PR's wiki/ directory.

[MaartenHilferink]

Already merged into working copy and pushed to wiki.