docs/DATAANALYSIS.md

DATAANALYSIS — what the curated data actually says

This document is the analytical companion to the curated parquet bundle produced by geography-vn curate. It walks through the 14-figure pack under docs/figures/analysis/ (rendered by scripts/analyze.py and embedded inline in DATAANALYSIS.ipynb) and tells the story of Vietnam after Resolution 202/2025/QH15 through the data alone.

Source: every number below comes from data/sapnhap-bando-vn/extracted/extracted.parquet (6,712 rows = 34 provinces + 3,321 communes + 3,357 commune people's-committee headquarters). The parquet was produced by the five-stage NeMo Curator pipeline described in DATAPROCESSING.md.

TL;DR

Stat	Value
First-level units (post-merger)	34
Second-level units (post-merger)	3,321
People's-committee headquarters	3,357
Total Vietnam population (2024)	113,571,926
Total Vietnam land area (km²)	331,325.62
Largest province by population	TPHCM — 14,002,598
Largest province by area	Lâm Đồng — 24,233 km²
Densest province	Hà Nội — 2,621 / km²
Most-merged commune	Phường Văn Miếu - Quốc Tử Giám — 16 predecessor wards
Distinct authorising decrees	37
Provinces that kept their old borders	11 out of 34

1 — Inventory (fig 01)

The atlas publishes three entity kinds, in roughly equal sub-counts:

Kind	Count	What it is
province	34	First-level admin units (28 provinces + 6 cities)
commune	3,321	Second-level units (phường / xã / đặc khu after the merger)
committee	3,357	Commune people's-committee headquarters (point markers)

The committee count slightly exceeds the commune count (3,357 > 3,321) because some communes have multiple registered committee buildings (the seat plus a satellite office) and a handful of pre-merger committees remain marked on the map even after their parent commune dissolved.

2 — Macro-region balance (fig 02)

The 34 surviving provinces redistribute across the six GSO macro-regions unevenly. The north (where the 2025 merger was the most aggressive) keeps 10 + 5 = 15 provinces under two macro-regions; the centre keeps 8 + 3 = 11; the south keeps 3 + 5 = 8. Including the people's-committee tier (which inherits its parent province's region):

Macro-region (EN)	Provinces	Communes	Committees	Total
Northern Midlands and Mountain Areas	10	841	842	1,693
Red River Delta	5	527	502	1,034
North Central and Central Coastal Areas	8	738	737	1,483
Central Highlands	3	361	380	744
Southeast	3	359	358	720
Mekong River Delta	5	495	537	1,037
(unknown — disputed-zone duplicates)	0	0	1	1

Note that the Northern Midlands retains the highest count of first-level units (10) despite being the region the merger consolidated hardest — pre-merger it had 14 provinces. The Southeast ends up the smallest by province count (3) because TPHCM swallowed both Bình Dương and Bà Rịa-Vũng Tàu into a single mega-city.

3 — Province population (fig 03)

The top-five most populous provinces, after the merger:

Rank	Province	Population	Area (km²)	Density (/km²)	Predecessors
1	Thành Phố Hồ Chí Minh	14,002,598	6,772.59	2,067.5	3
2	Thủ Đô Hà Nội	8,807,523	3,359.84	2,621.4	1
3	Tỉnh An Giang	4,952,238	9,888.91	500.8	2
4	Thành Phố Hải Phòng	4,664,124	3,194.72	1,460.0	2
5	Thành phố Đồng Nai	4,491,408	12,737.18	352.6	4

TPHCM's merger absorbed Bình Dương (industrial belt) and **Bà Rịa

• Vũng Tàu** (the southern coast & Côn Đảo) into one super-city, doubling its population from ~7 M to 14 M — now larger than New York's metro.

Đồng Nai is the only province in the country that absorbed four predecessor units (the original Đồng Nai + Bình Phước + parts of two neighbours), making it the largest-area populated unit in the south.

4 — Province area (fig 04)

The top-five largest provinces by km², all in the central highlands or upper-central coast:

Rank	Province	Area (km²)	Population	Density (/km²)	Predecessors
1	Tỉnh Lâm Đồng	24,233.07	3,872,999	159.8	3
2	Tỉnh Gia Lai	21,576.53	3,583,693	166.1	2
3	Tỉnh Đắk Lắk	18,096.40	3,346,853	184.9	2
4	Tỉnh Nghệ An	16,486.50	3,831,694	232.4	1
5	Tỉnh Quảng Ngãi	14,832.55	2,161,755	145.7	2

Lâm Đồng is the merger's largest single creation: the old Lâm Đồng + Bình Thuận (south-central coast) + Đắk Nông (Central Highlands) fused into a 24,233 km² province that now stretches from the central plateau to the South China Sea coast.

5 — Province density (fig 05)

Rank	Province	Density (/km²)	Population	Area (km²)
1	Thủ Đô Hà Nội	2,621.4	8,807,523	3,359.84
2	Thành Phố Hồ Chí Minh	2,067.5	14,002,598	6,772.59
3	Thành Phố Hải Phòng	1,460.0	4,664,124	3,194.72
4	Tỉnh Hưng Yên	1,418.8	3,567,943	2,514.81
5	Tỉnh Ninh Bình	1,119.1	4,412,264	3,942.62

Hà Nội remains the densest province even though it kept its pre-merger borders unchanged (its n_predecessors == 1). Hưng Yên, post-merger absorbing Thái Bình, jumps into the top 4 — the merged Red River Delta provinces concentrate density there.

6 — Communes per province (fig 06)

The lower-tier consolidation is more uneven:

• Min: 38 communes (Tỉnh Lai Châu — sparsely populated mountains)
• Max: 168 communes (Thành phố Hồ Chí Minh — mega-city)
• Median: 99 communes per province
• Mean: 97.7 communes per province

Bottom five (sparsest):

Province	Communes
Tỉnh Lai Châu	38
Thành phố Huế	40
Tỉnh Điện Biên	45
Tỉnh Quảng Ninh	54
Tỉnh Cao Bằng	56

Top five (densest):

Province	Communes
Thành phố Hồ Chí Minh	168
Tỉnh Thanh Hóa	166
Tỉnh Phú Thọ	148
Tỉnh Gia Lai	135
Tỉnh Nghệ An	130

7 — Province merger fanout (fig 07)

How many predecessor provinces fed each surviving first-level unit:

n_predecessors	Provinces	Names
1	11	Hà Nội, Huế, Cao Bằng, Điện Biên, Hà Tĩnh, Lai Châu, Lạng Sơn, Nghệ An, Quảng Ninh, Sơn La, Thanh Hóa
2	16	Đà Nẵng, Hải Phòng, An Giang, Bắc Ninh, Cà Mau, Đắk Lắk, Đồng Tháp, Gia Lai, Hưng Yên, Khánh Hòa, …
3	6	Cần Thơ, Hồ Chí Minh, Lâm Đồng, Ninh Bình, Phú Thọ, Vĩnh Long
4	1	Đồng Nai

Eleven provinces kept their old borders — they were already large enough or geographically isolated enough that the merger left them alone. The modal merger absorbed exactly one neighbour. Đồng Nai is the singular four-way merger.

8 — Commune merger fanout (fig 08)

The lower tier was consolidated much more aggressively. Of the 3,321 surviving communes:

n_predecessors	Communes	%
1	139	4.2%
2	758	22.8%
3	1,498	45.1%
4	559	16.8%
5	179	5.4%
6	78	2.3%
7+	110	3.4%
max	16

The modal commune absorbed 3 predecessor wards/xã. The mean fanout is 3.4 (compared to ~1.6 for the first-level tier).

The most-merged commune is Phường Văn Miếu - Quốc Tử Giám in Hà Nội, which fused 16 predecessor wards into a single 4-character neighbourhood. Hà Nội dominates the high-fanout extreme — 8 of the top 15 communes by fanout are in Hà Nội, reflecting the post-merger desire to flatten the dense old ward grid into larger, more administratively manageable units. The other notable mega-mergers are coastal special zones: Đặc khu Cát Hải (Hải Phòng, 12 preds), Đặc khu Vân Đồn (Quảng Ninh, 12 preds).

9 — Commune size distribution (fig 09)

A log-log scatter of commune area vs population reveals three regimes:

• Special administrative zones (Đặc khu) — sit in the bottom-left: tiny populations on tiny islands. Hoàng Sa (the Paracels — 0 registered population, 350 km²), Trường Sa (Spratly — 153 people, 496 km²), Cồn Cỏ (139 people, 2.3 km²), Bạch Long Vĩ (686 people, 3.07 km²). All have ambiguous-to-disputed sovereignty status and serve mainly as markers of national territory.
• Highland xã — the upper-left band: tens of thousands of inhabitants spread across 200-1100 km² of mountain terrain. Buôn Đôn (Đắk Lắk, 1,114 km², 6.6K people) is the largest by area in the entire set. The Trường Sơn cordillera communes in Quảng Trị (Thượng Trạch, Trường Sơn, Kim Ngân) all exceed 800 km² each.
• Urban phường — the lower-right cluster: 50-130K people on a few km² of city. Phường Hải Châu (Đà Nẵng, 7.58 km², 131K people) is the densest by far.

10 — Decree corpus (fig 10)

The merger is authorised by 37 distinct decrees: 1 from the National Assembly itself (Nghị quyết số 202/2025/QH15) and 34 follow-up Standing Committee resolutions (NQ-UBTVQH15) of 16 June 2025 that flesh out the lower-tier merger commune-by-commune. The top decrees by number of units cited:

Decree	Units cited
Nghị quyết số 1685/NQ-UBTVQH15	168
Nghị quyết số 1686/NQ-UBTVQH15	166
Nghị quyết số 1676/NQ-UBTVQH15	148
Nghị quyết số 1664/NQ-UBTVQH15	135
Nghị quyết số 1678/NQ-UBTVQH15	130
Nghị quyết số 1674/NQ-UBTVQH15	129
Nghị quyết số 1656/NQ-UBTVQH15	126
… (30 more)	…

Each NQ-1656…1690 decree corresponds to one of the 34 surviving provinces. The top decree (NQ-1685) authorises all 168 wards of TPHCM; NQ-1686 covers the 166 communes of Thanh Hóa; etc. Every commune row in the parquet has a decree_url column pointing to the official text at vanban.chinhphu.vn.

11 — Cartographic pack with dual-archipelago declaration

Geographic visualisations live in their own folder under docs/figures/maps/ — rendered standalone by python -m scripts.render_maps because kaleido + Mapbox-GL crashes inside a Jupyter kernel. Five figures total, each with the actual scraped province polygons (not bubbles) and the standard Vietnamese-atlas declaration of both offshore archipelagos:

• Quần đảo Hoàng Sa (Paracel Islands) — dashed bounding outline ~15.45°N–17.20°N × 110.85°E–113.10°E with markers for Phú Lâm, Tri Tôn, Linh Côn, Quang Hòa. Administered by Thành phố Đà Nẵng under the post-2025 geography (Đặc khu Hoàng Sa).
• Quần đảo Trường Sa (Spratly Islands) — dashed bounding outline ~7.40°N–11.85°N × 111.80°E–115.30°E with markers for Trường Sa Lớn, Song Tử Tây, Sinh Tồn, Phan Vinh, An Bang, Nam Yết, Cô Lin, Sơn Ca. Administered by Tỉnh Khánh Hòa (Đặc khu Trường Sa).

Each map additionally carries: ★ Thủ đô Hà Nội (capital), 7 secondary cities (TP. Hồ Chí Minh / Đà Nẵng / Hải Phòng / Huế / Vinh / Cần Thơ / Nha Trang) with leader-line labels into open sea, and 5 island callouts (Đảo Phú Quốc / Cát Bà / Bạch Long Vĩ / Lý Sơn + Côn Đảo).

File	Visualisation
maps/01_provinces_population.png	population choropleth (sequential NVIDIA-green)
maps/02_provinces_density.png	people / km²
maps/03_provinces_area.png	land area (km²)
maps/04_communes_scatter.png	3,321 commune centroids by macro-region
maps/05_committees_scatter.png	3,357 commune people's-committee headquarters by lat/lon

The cartographic pack uses NVIDIA Sans typography on a square 1100 × 1100 canvas; the analytical pack above uses the LaTeX-serif nvidia_latex template at 1200 × 900. Maps follow brand convention, charts follow academic-paper convention.

12 — Curator UMAP (fig 11, fig 12)

A 2-D UMAP projection of the 6,712-point sentence-transformers embedding of every entity's embed_text descriptor. Three observations:

1. Kind separation is partial. Provinces and committees occupy compact, well-separated tail regions of the map (provinces because their descriptors include rich predecessor-province prose that other entities do not; committees because every committee description follows the standard "Ủy ban nhân dân …" template). Communes fill the middle and overlap with both extremes.
2. Macro-region structure emerges. Even though the embed text does not explicitly mention macro-region, the UMAP × macro-region colouring shows clean lobes for the Mekong Delta, the Northern Midlands, and the Central Highlands — the model picks up on regional naming conventions (Đặc khu Phú Quốc clusters with the southern coast, Xã Mường Khương with the Northwest, etc.).
3. HDBSCAN finds ~30-50 dense subclusters within the broader regional structure. Most are sub-province-level: a single province's communes cluster together because their descriptors share a common parent_ten tag, the same parent decree, and similar predecessor-name patterns ("Phường … và Phường … sau khi sắp xếp"). The cluster column in reduced.parquet carries the integer label per row, with -1 reserved for low-density noise points.

Caveats & known limits

• Đặc khu Hoàng Sa has zero registered population. The Paracel Islands are administered by the People's Republic of China and have not been physically Vietnamese-controlled since 1974. The Vietnamese atlas marks them as a special administrative zone of Đà Nẵng with a populations of zero — a sovereignty assertion, not a usable demographic figure.
• Population numbers are 2024 mid-year estimates as published with the merger decrees (rounded thousands at the commune level). They predate the merger by 6–12 months and may not yet reflect intra-merger population migration.
• Two parent-province strings come back inconsistent: "Thủ đô Hà Nội" vs "Thủ Đô Hà Nội" (different Đ/đ capitalisation depending on the endpoint). The parent_ma column normalises this — join on parent_ma not on parent_ten for analysis.
• 3 communes carry the name "Xã Hoàng Hoa Thám" (each in a different province) and 1 carries "Đặc khu Phú Quốc". Use id (== feature id) not ten as the primary key.
• The committee macro-region is derived from the GeoJSON properties.a04_tentinh field, which can be missing for ~20 of the 3,357 committees (mostly defunct pre-merger seats). Those rows show macro_region == "unknown" in the parquet.

How to reproduce

# 1) Download + curate (~35 min on first run, then cached)
geography-vn curate

# 2) Render the figure pack (~2 min)
python -m scripts.analyze

# 3) Re-execute the notebook (optional)
jupyter nbconvert --to notebook --execute --inplace DATAANALYSIS.ipynb

# 4) Stage and push the HF dataset
python -m scripts.upload_to_hf --no-upload
python -m scripts.upload_to_hf --repo <your-org>/sapnhap-bando-vn

See DATAPROCESSING.md for the curator-pipeline internals.