Recently someone asked how to find OSM users who’ve left a changeset comment, but have not edited themselves. (Technically the initial challenge was for a one line bash script 😉).

Here’s how to do it.

In OpenStreetMap, people can change their username, but OSM data provides an unchanging numeric user id (uid) for users, which we use here.

First download the dump file, from the OpenStreetMap data download serivce (planet.osm.org) ⁽¹⁾.

aria2c --seed-time=0 https://planet.openstreetmap.org/planet/discussions-latest.osm.bz2.torrent

This will download discussions-YYMMDD.osm.bz2⁽²⁾, which is currently about 5 GiB.

I had to write a new tool, anglosaxon to easily parse large XML files like this into a TSV file format⁽³⁾. This programme works on all XML files, maybe it’s useful for other problems you might have. Install that first.

bzcat discussions-220110.osm.bz2 \
  | anglosaxon \
   -S -o changeset_id --tab -o changeset_uid --tab -o comment_uid --nl \
   -s comment -v ../../id --tab -V ../../uid NO_CHANGESET_UID --tab -V uid NO_COMMENT_UID  --nl \
   | gzip > changeset-comments.tsv.gz

This took about 45 minutes to run on my machine, and the output is about 4 MiB (19 MiB uncompressed), and has about 805,000 lines. This step takes the longest.

We create the list of all uids who have opened a changeset:

zcat changeset-comments.tsv.gz | cut -f2 |uniq|sort |uniq > changeset-uids.tsv

Then a list of all uids who have left a changeset comment:

zcat changeset-comments.tsv.gz | cut -f3 |uniq|sort|uniq > comment-uids.tsv

Then we compare, what’s in one but not the other.

comm -13 changeset-uids.tsv comment-uids.tsv |sort -n > uids-comment-without-changeset.tsv

Et voilà! Sin é! And there’s your results. 🙂 The file is 29 KiB, and has ~3,500 entries. I’m surprised it’s so high.⁽⁴⁾

You can find all the changesets that a uid has commented on with this command, (replace UID with the uid)

zcat changeset-comments.tsv.gz | grep -P "\tUID$" | cut -f1

e.g. the comments that uid 23770⁽⁵⁾ has commented on:

zcat changeset-comments.tsv.gz | grep -P "\t23770$" | cut -f1

The OSM API has several methods to get details on an OSM user, e.g.:

curl "https://api.openstreetmap.org/api/0.6/user/23770"

---

⁽¹⁾ Here we use aria2c which will do a regular web/HTTP download, and also use BitTorrent P2P decentralized downloads in addition. --seed-time=0 stops aria2c when the file is fully downloaded, rather than sharing/seeding the file forever over BitTorrent

⁽²⁾ YYMMDD is the year, month & date that the data was created

⁽³⁾ tab separated values, like CSV, but with tabs

⁽⁴⁾ If you’re curious of how to do that on one line using bash(1)’s Proccess Substitution:

comm -13 <(cut -f2 changeset-comments.tsv |uniq|sort|uniq) <(cut -f3 changeset-comments.tsv |uniq|sort|uniq) | sort -n > uids-comment-without-changeset.tsv

⁽⁵⁾ My user id