After the map tag from yesterday, here are two more plugins I built to make this blog feel like a proper GIS tool.

One is for GPX tracks — drop a file from your GPS, get a map with the full track and an elevation profile. The other is for data tables — take a CSV or GeoJSON and get a sortable table without touching JavaScript.

Both work the same way: one Liquid tag, no scripts, no includes.

GPX Track with Elevation Profile

Here is a GPX track from a hike at Bukit Lima in Sibu — about 4.8km with ~280m of gain:

Distance

1.85 km

Gain

+280 m

Loss

−280 m

Elevation

25–305 m

That is just:

{% gpx_track file="/assets/datasets/demo_hike.gpx" caption="Bukit Lima Summit Trail..." %}

The map, the SVG elevation profile, and the stats (distance, gain, loss, elevation range) are all generated at build time. The elevation chart is an inline SVG — no JavaScript charting library needed.

The start and end points get circle markers so you can see which direction the track runs. The map auto-fits to the track bounds.

Sortable Data Table from CSV

If you work with field data, you know how tedious it is to copy-paste attribute tables into markdown. This tag reads a CSV file and gives you a sortable table:

Sarawak forest survey sites, 2024 field season

site_id	name	land_cover	elevation_m	date_surveyed	species_count	notes
SG-01	Bako National Park	Mangrove	12	2024-03-15	47	High proboscis monkey activity
SG-02	Gunung Gading	Dipterocarp	450	2024-04-02	82	Rafflesia spotted at km 3.2
SG-03	Kubah National Park	Kerangas	180	2024-04-18	63	Orangutan nest count: 14
SG-04	Santubong Peninsula	Mixed dipterocarp	310	2024-05-10	91	Good canopy access via existing trails
SG-05	Bako Terminal	Beach forest	5	2024-05-22	28	Erosion monitoring site
SG-06	Lambir Hills	Lowland dipterocarp	265	2024-06-05	124	Long-term 52-ha plot
SG-07	Similajau Coast	Beach	8	2024-06-20	19	Sea turtle landing site
SG-08	Usun Apau Plateau	Montane	980	2024-07-01	56	Accessible by logging road only
SG-09	Mulu Summit trail	Limestone forest	1200	2024-07-12	44	Nepenthes rajah zone
SG-10	Maludam Peninsula	Peat swamp	3	2024-07-25	35	Rare stork colony

Click any column header to sort. Click again to reverse. Numeric columns like elevation and species count sort by value instead of alphabetically.

You can also filter which columns to show and pick a default sort:

Filtered to four columns, pre-sorted by species count (most diverse first)

site_id	name	elevation_m	species_count
SG-07	Similajau Coast	8	19
SG-05	Bako Terminal	5	28
SG-10	Maludam Peninsula	3	35
SG-09	Mulu Summit trail	1200	44
SG-01	Bako National Park	12	47
SG-08	Usun Apau Plateau	980	56
SG-03	Kubah National Park	180	63
SG-02	Gunung Gading	450	82
SG-04	Santubong Peninsula	310	91
SG-06	Lambir Hills	265	124

From GeoJSON Too

The same tag works with GeoJSON — the feature properties become the columns:

Borneo Kolomee Trail — waypoints from GeoJSON

overview	order	headline	text	media	caption	credit
1	0	The Great Sarawak Kolo Mee Trail	<p>A (completely fictional) culinary expedition across Borneo in search of the perfect bowl of <em>kolo mee</em>. Five towns, five legends, zero calories counted. Buckle up — the noodles are calling.</p>	https://en.wikipedia.org/wiki/Kolo_mee	Warning: contains dramatised noodle facts.	Ministry of Imaginary Cuisine
1	Kuching — The Origin Bowl	<p>Legend says the very first bowl of kolo mee was tossed here at 3:47 a.m. by a cat who refused to sleep. Locals still leave out a saucer of char siu in tribute. The city's stray cats are rumoured to review hawker stalls with a strict five-whisker rating system.</p>	https://en.wikipedia.org/wiki/Kuching	Cat City. Coincidence? The felines think not.	Whisker Times	Kuching	8	http://maps.gstatic.com/intl/en_us/mapfiles/ms/micons/blue-pushpin.png	1	1908-01-01
2	Mukah — The Sago Detour	<p>Our expedition briefly abandons noodles for <em>umai</em> and sago pearls. Scientists (imaginary ones) estimate that Mukah produces enough sago each year to build a bouncy castle the size of a small island. No one has tried. Yet.</p>	https://en.wikipedia.org/wiki/Mukah	Sago: chewy, wobbly, structurally underrated.	Institute of Bouncy Studies	Mukah	8	http://maps.gstatic.com/intl/en_us/mapfiles/ms/micons/blue-pushpin.png	1
3	Sibu — The Kampua Rivalry	<p>Here the trail turns tense. Sibu insists its <em>kampua mee</em> is the true champion, not kolo mee. Diplomatic noodle summits are held nightly at the pasar. So far, the only treaty signed is that everyone orders a second bowl.</p>	https://en.wikipedia.org/wiki/Sibu	Neutral ground: the shared chilli sauce bottle.	Council of Noodle Affairs	Sibu	8	http://maps.gstatic.com/intl/en_us/mapfiles/ms/micons/blue-pushpin.png	1
4	Bintulu — Refuel at the Energy Town	<p>Powered by natural gas and, apparently, unlimited belacan, Bintulu is where our travellers refuel — both the van and themselves. Local myth claims a bowl of noodles here gives you enough energy to walk to Miri. It does not. We checked.</p>	https://en.wikipedia.org/wiki/Bintulu	Fuel gauge: full. Stomach gauge: fuller.	Department of Optimistic Distances	Bintulu	8	http://maps.gstatic.com/intl/en_us/mapfiles/ms/micons/blue-pushpin.png	1
5	Miri — The Final Bowl	<p>The trail ends where it began, in oil-town Miri, with a sunset, a seahorse mascot, and the biggest bowl of kolo mee anyone dared to order. Verdict after 1,200 km: they are all the best. This is the only scientifically imaginary conclusion possible.</p>	https://en.wikipedia.org/wiki/Miri,_Malaysia	The Seahorse City approves this expedition.	Bureau of Happy Endings	Miri	8	http://maps.gstatic.com/intl/en_us/mapfiles/ms/micons/blue-pushpin.png	1

The Whole Toolkit

At this point the blog has six custom Liquid tags covering pretty much everything I need for GIS writing:

No webpack, no npm, no node_modules. Everything that can be computed at build time — GeoJSON transforms, CSV parsing, SVG generation, GPX stats, Haversine distances — is. The only runtime dependencies are Leaflet and MapLibre from CDN, and those are loaded once per page.

For a solo GIS blog, this is about as good as it gets.