Symbol Maps
Learn how to build symbol maps, representing data values through varying symbol sizes or shapes over geographic areas.
Overview
Symbol Maps display data from a symbol field on defined points of latitude and longitude. Various symbol shapes can be selected, and they can be assigned both color and size dimensions.
Symbol maps are commonly used in fields such as geography, environmental science, and urban planning to display the distribution of data points across a geographic area. By representing data values with symbols of varying size, shape, or color, these maps allow end users to quickly identify patterns and concentrations, such as the locations of natural resources, infrastructure, or event occurrences.
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
Symbol 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 symbol 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 symbols, it establishes the visible area in which the symbols are displayed.
In this map of U.S. airport traffic, the basemap is a contextual background layer and is not connected with the overlaid airport data in any way.
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
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.
Symbols
In the Symbol section, you can adjust various properties related to the size and appearance of the symbols:
- Symbol Shape: Set the shape of the symbols on the map. The default is set to Circle.
- Dynamic and Fixed Sizes: Choose to have a uniform size for all symbols on the map (fixed) or scale the symbols based on data values (dynamic). You can choose fixed if you only want to vary the symbol color while keeping the size consistent.
- Symbol Size: The Symbol Size Field controls the size of symbols based on the values it contains. The Maximum Symbol Size field sets the symbol’s size when the value in the Symbol Size Field reaches the Maximum Symbol Value. Other values are scaled proportionally. If Maximum Symbol Value is set to "auto," it defaults to the largest value in the Symbol Size Field.
- Border: You can specify a Border Width for all symbols on the map. By default, the border shares the same color as the symbol, making it blend in unless the symbol's Opacity, set in the Colors menu, is reduced below 100%. Alternatively, you can apply a Custom Border Color, which assigns the same border color to all symbols, regardless of their inner fill color.
This Symbol Map displays recorded meteor strikes across Australia, with each circle representing a strike. Major cities have been added to the map using annotations.
Annotations
In the Annotations section under the Map tab, you can add annotations consisting of text and/or symbols to your map.
Begin 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.
