Arrow Maps
Learn how to build arrow maps, representing data values through varying arrow sizes over geographic areas.
Overview
Arrow Maps display data from an Arrow Height field on defined points of latitude and longitude. Various arrow angles can be selected, and each arrow can be assigned a color dimensions.
Arrow maps use directional arrows to represent changes in values across geographic areas. They are especially useful for visualizing differences between two points in time or two comparative metrics—for example, showing shifts in political trends between electoral cycles or changes in populations or demographics.
Setup
After inserting a map, navigate to the
Map tab in the right panel. In the
Setup section, you can assign basic properties to the map, which are detailed on the
Maps overview page. Next, open the
Map Type section and click on
Arrow Map.Connecting to a Basemap
In the Basemap section under the Map tab, you can select an underlying basemap for your map element. The basemap is a map, stored in GeoJSON format, consisting of features (geographical shapes) such as countries, provinces, and electoral districts. In order to add a basemap to a map element, you must first add a basemap to your project. This can be done by selecting New Basemap in the Project tab. Clicking Find Basemap then opens a library of more than 600 basemaps to choose from.
In arrow maps, the basemap serves as a background layer, defining the geographic extent of the map container. While the basemap itself is not connected to the overlaid arrows, it establishes the visible area in which the symbols are displayed.
Connecting to Datasets
In the Dataset section, you can select the dataset for your map element, which contains the data that you wish to display on the map. In order to add a dataset to a map element, you must first add a dataset to your project. This can be done by selecting New Dataset in the Project tab.
If you are on the Pro plan, you can upload your own files (in csv format) to use as datasets, by clicking New Dataset and then Upload Dataset.
After you have selected a dataset, you can optionally enable the Prefilter Dataset switch, which lets you filter the data that is supplied to the map. The filter is a "prefilter" because it is applied before the visualization is generated; end users are unable to adjust the filter dynamically.
Next, select Latitude and Longitude fields. These are fields (columns) within the selected dataset that will determine the location of each symbol record on the map element. Both fields must be assigned the Coordinate data type in the dataset editor.
Join Fields
Join fields allow properties defined in the basemap file to be associated with fields in the selected dataset. While join fields are not required for this map type (because data is placed on the map by means of the specified latitude and longitude fields), they can still be optionally specified for the two reasons outlined below.
First, adding join fields allows you to filter the basemap's features, when used in tandem with the Hide Filtered Features option (found under the map's Settings tab).
Second, adding join fields lets you annotate each basemap feature using the Annotation Field found under the Auto section of the map's Annotations tab.
Connecting to Filters
You can establish connections to filter elements under the Map tab, in the Connections section, by making a selection under Filter.
Filter elements display values from a specified
Filter Field, in the form of checkboxes, dropdown menu items, or (for numeric filtering) slider values. A given map can be connected to one or more filters, and the same filter can be connected to multiple maps or other elements. Once connected to a map, a filter element will dynamically control the dataset records passed to the map element, based on user selections made on the filter.
For more details about connecting to filters, see the main
Maps page.
Colors
In the
Colors section under the
Map tab, you can assign a
Color Field from the selected dataset. Choose either a text or numeric field (e.g., number, currency, percent, or measurement). For text fields, each unique value becomes a category that can be assigned a specific color. For numeric fields, you can configure a
Color Gradient, set
Domain Minimum and
Maximum values, and define the
Color Scale. Additionally, you can assign a
Missing Data Color and adjust the default
Opacity. For more details, see our
Colors page.
You can also assign a fixed color to all symbols on the map. This is useful when you only want to vary the symbol size while keeping the color consistent.
Arrows
In the Arrows section, you can add an Arrow Height Field and adjust various properties related to the size and appearance of the arrows:
- Use the Arrow Height Field to select the field that should be used to determine the height of the arrow.
- The Maximum Arrow Height determines the length of arrows that have the Maximum Arrow Value.
- Set the Positive Angle and Negative Angle to define the orientation of arrows that are positive and negative respectively.
- Line Width determines the width of the lines used to construct each arrow.
Annotations
In the Annotations section under the Map tab, you can add annotations consisting of text and/or symbols to your map.
Under Auto, you can specify an Annotation Field, which centers an annotation label on each map feature (i.e. geographic shape).
Under Custom, you can add custom annotations by picking a longitude and latitude to place the annotation on the map. You can then choose either or both of the following two options:
- Add Text: Add some Text, pick a Color, and specify the Text Position in relation to the chosen longitude and latitude.
- Add Symbol: Choose a Symbol Shape, a Color for the symbol, and a fixed Width in pixels.
Under Settings, select the Hidden Annotation Width. Annotations will be hidden when the map's width, in pixels, is between 0 and this value. This gives you the option of hiding annotation text when the map is resized to narrow windows or devices.
