How to import markers into locator maps

You can import point, area, and line markers to Datawrapper locator maps. This article explains the requirements for those files, and how to import them.

Contents

1. Importing files into Datawrapper
2. Prerequisites for all kinds of markers
3. Prerequisites for point markers
4. Prerequisites for arrow markers
5. How to keep your map loading quickly

Importing files into Datawrapper

There are three ways to get your files into your locator map. Make sure you're in step 1: Add markers for all of them.

The first option is to simply drag them in there, like in the video above.

The second option is to select which kind of marker you want to add – point, area, line, or arrow – then click on the little upload button in the bottom right corner and choose the file from your computer.

The third option is to paste data into the text field that says Paste data here or drag it onto the page. You can paste the content of any file specific in the beginning of the article. You can even paste data directly from Excel or Google Sheets:

Prerequisites for all kinds of markers

You can successfully import a file into a Datawrapper locator map if it:

• Is a GeoJSON, CSV, GPX or KML file.
• Is smaller than 2MB. You can upload files up to 10MB in size, but the markers they result in (after Datawrapper removes e.g. the CSV columns irrelevant to the marker) plus the existing markers on the map have to be less than 2MB. The larger your file, the longer it takes for your map to load for both viewing and editing. Try to keep it as small as possible.
• Includes coordinates.
• Uses the WGS-84 coordinate system (EPSG:4326), if you import GeoJSON, GPX or KML.
• Has fewer than 20 differently styled features. Learn how to style your markers before importing them to Datawrapper here.

You can import lines, areas, and points together in one geo data file.

Prerequisites for point markers

You can import point markers with a CSV, GeoJSON, GPX or KML file. The easiest way is to use a CSV. All you need are two columns – one for the longitudes (called lon, lng, longitude, or y) and one for the latitude (called lat, latitude, or x).

You can also customize your markers before importing them, but it's not necessary. Here's an example of a valid CSV:

lon,lat
6.725654,7.202151
12.810290,11.7662530
-0.8427773,12.839212

Prerequisites for arrow markers

You can import arrows either as a CSV or a GeoJSON.

If you're preparing a CSV, make sure it has the following columns (they don't need to be in that order): arrow_start_lon, arrow_start_lat, arrow_end_lon, arrow_end_lat

They define the coordinates (lat and lon) of both the start of the arrow and the end of the arrow. Here's an example:

arrow_start_lon,arrow_start_lat,arrow_end_lon,arrow_end_lat
4.8897,52.3740,13.4050,52.5200
2.3522,48.8566,9.1900,45.4642
18.0686,59.3293,23.7275,37.9838

If you're preparing a GeoJSON, use a LineString with two coordinate points and set “type”: “arrow” in the properties. If you want to import a lot of arrows, you can also use a MultiLineString that has 1+ lines with two coordinate points. Here's an example:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "type": "arrow"
      },
      "geometry": {
        "coordinates": [
          [-0.1276, 51.5074],
          [13.4050, 52.5200]
        ],
        "type": "LineString"
      }
    }
  ]
}

Note that in the same CSV or GeoJSON, you can also upload other marker types. You can, for example, add lat and lng columns in your CSV and add coordinates in those columns that would be shown as point markers after importing the file to Datawrapper.

How to keep your map loading quickly

If you upload GeoJSONs that are very big or that have many different markers, your map will be slower for both you (in the editing process) and your readers (when they view the website where you embedded the map).

There are a few ways to make sure your map stays performant:

• Group your markers together to reduce their number. Learn more in our article "How to group area markers before importing them."
• Style multiple lines or areas in your geo file in the same way before importing them to Datawrapper. If you do so, they get imported as one marker. Learn more in our article "How to style your markers before importing them to Datawrapper."
• Reduce the file size by simplifying your geometry. To do so, go to mapshaper.org, upload your GeoJSON, then click the "Simplify" button in the upper right, followed by "Apply." Drag the slider at the top as far to the right as you can while the geometry still looks good enough. The displayed percentage tells you how much of the data size is left. Typically you can go down to 10-15% without noticing a big difference. When you're done, click "Export," select GeoJSON, and re-upload the data to Datawrapper.
• Reduce the file size by removing information. When you import a GeoJSON, all features in it are imported and count toward your map size, so it's worth removing any properties you don't need beforehand. (When importing point markers via CSV, Datawrapper only uses the relevant columns – lat/lon, title, tooltip, etc. – and discards the rest, so there's little point in cleaning up.)