As an Easter present for you all, I’ve got a new web app you can play with. It lets you search for UK place names – things like ‘ends with burgh’ or ‘starts with great’ or ‘contains sea’ – and then plot them on an interactive map. Once you’ve done that, you can even share […]
This is only about 3 years late – but I gave a talk at FOSS4G 2021 on geospatial PDFs. The full title was: From static PDFs to interactive, geospatial PDFs, or, ‘I never knew PDFs could do that!’ The video is below: In the talk I cover what a geospatial PDF is, how to export […]
Here’s a bit of SQL I wrote recently that had an error in it which I struggled to find. The error I got was ERROR: invalid reference to FROM-clause entry for table "roads" and I did some Googling but nothing really seemed to make sense as a cause of this error. My SQL looked like […]
Summary: If appending to a PostGIS table with GDAL/OGR is taking a long time, try setting the PG_USE_COPY config option to YES (eg. adding –config PG_USE_COPY YES to your command line). This should speed it up, but beware that if there are concurrent writes to your table at the same time as OGR is accessing […]
I use GeoPandas for a lot of my vector GIS data manipulation in Python. I had a situation the other day where I ended up with duplicates of some geometries in my GeoDataFrame, and I wanted to remove them. The simple way to do this is to use the underlying pandas method drop_duplicates on the […]
Summary: The QGIS Reloader plugin will give you a new QGIS command to reload a layer, very useful when you’re updating a layer in another program and want to refresh QGIS’s view of it. I use QGIS for almost all of my interactive GIS needs. Often I’ll be writing some code in Python that creates […]
I’m giving two talks in the next two weeks, and wanted to publicise them here in case anyone local-ish wants to come. Oxford Cafe Scientifique I’ve spoken at various Cafe Scientifique meet-ups before, and now it’s the turn of the Oxford one. I’ll be giving my talk about the whole range of satellite imaging – […]
Just a quick one this time… GeoParquet is a cool new-ish format for geospatial data. I’ve tried to use it a couple of times, but always run into issues with my GDAL/OGR install not supporting it. Each time this has led to me giving up, as I couldn’t be bothered to install GDAL from somewhere […]
A fun analysis I did a while back was using the Google Maps API to look at travel times between certain locations over time. I originally got interested in this because I found that travelling from my house to the university (yes, that’s how long ago this started…) seemed to either take a very short […]
Following on from my last post on plotting choropleth maps with the leaflet-choropleth library, I’m now going to talk about a small addition I’ve made to the library. Leaflet-choropleth has built-in functionality to automatically categorise your data: you tell it how many categories you’d like and it splits it up. However, once I’d set up […]