If your data relates to administrative areas (countries, local authorities, constituencies, regions, police forces, CCGS) then you will need to create a choropleth map. This is a map that shows shapes instead of points.
To do this you need at least two sets of data:
- The data containing the names or codes for the areas and any values you want to show
- Data containing the coordinates of the areas - often called shape files
Luckily, a number of data visualisation tools have the second part built in for certain areas. Flourish, for example, has constituencies and local authorities (and London boroughs only) for the UK and Great Britain, as well as European countries and administrative districts for countries including the US, Spain and India. Datawrapper has even more, including police force areas and CCGs.
However, if Datawrapper or Flourish does not have the areas you want to use, you will need to find the data for those shapes, in GeoJSON format (you can convert to this format from others, such as KML or Shapefile).
Both are also somewhat limited when it comes to showing just one region: because all the shapes are at a national level, if your data only relates to one region then there is no way to exclude the rest, and in most cases zoom levels don't go in close enough to address this. In this situation you will also need a shapefile for the specific area.
Those two datasets - the area names/codes and values, and the area shapes - will need to match up in some way. In other words, the names or codes in the shapes dataset will need to match up with some names or codes in your values dataset.
Before mapping, it's a good idea to check that this is the case, and clean up any that don't match. That's especially likely if you are matching on names rather than codes, because your version might use 'and' where the shapes data might use '&' or have other slight variations in naming.
Flourish, in fact, doesn't use codes for its shapes, which makes it more vulnerable to this problem.
To check, then, go to Flourish's templates page at https://app.flourish.studio/templates and scroll down to the Projection map section. Click on the Great Britain (local authorities) map to start creating one.
A new visualisation should open. It will be in Preview view, where you can see the map you are creating.
Switch to the Data view by clicking on that tab towards the top of the screen.
There will be a Regions data tab, and a Points one.
The Points table has some default data showing certain cities. Delete all this.
The Regions table has 3 columns: geometry, id and Value.
Click on the drop-down arrow on the Regions tab and select Download data - select Current sheet only.
You will now have a copy of the data from the map. In the Values column use a VLOOKUP formula to fetch the values from your own data so that you have the values you want to visualise.
Chances are that in some cases the formula will give you an error (sort the column to bring these to the top). These will be the ones with some slight variation in naming - so go to the original data and check that the places are named the same.
Once you've finished cleaning up the data, you can return to Flourish and click Upload data file in the upper right corner of the data, and upload that file.
Switch to the Preview tab and you should now see those values visualised on your map.
Use the options on the right to customise your map, adding a heading and intro, footer, and trying different colours etc.
There is a very simple way of limiting your visualisation to certain authorities or constituencies - delete all the others entirely.
When you download the data, sort it to bring all the ones you want to keep to the top (e.g. sort by value if some don't have any), and then delete the rows you want to omit.
When you upload it, the map will only show those areas.
If you want to show other sorts of areas that aren't already in the data visualisation software, then you'll need to find the data describing those areas. Ideally these should be in GeoJSON format. For example you can use Martin Chorley's UK-GeoJSON tool to generate JSON files of different local authorities (divided into sub-areas such as LSOA or constituency - these will work in Datawrapper but not Flourish)
Often you will find these in Shapefile format, or KML. For example, most of the ONS files on geographic boundaries at http://geoportal.statistics.gov.uk/ (select the Boundaries menu) are provided in that format (click on Download and you should get options for KML or Shapefile).
In those cases you will need to convert to GeoJSON so that it will be recognised by Datawrapper or Flourish.
If that's the situation Google "convert shapefile to geojson" and try one of the tools that you find, e.g. https://mapshaper.org/
Once you've got a GeoJSON file, go into Flourish to create a new visualisation, scroll to the Projection map section, and click on the first option: Blank (upload your own) then upload the file to the Regions tab.
As before, you can now download this and match with other data.