Maps allow you to visualize data in a variety of ways. For example, you can visualize population data for countries as a sequence of colors, such as from light to dark, or as proportional circles, such as from small to large. This flexibility allows you to tell different stories and discover hidden patterns depending on how the data is presented. However, because mapmaking is so flexible, you must make decisions when there isn't always a single best answer.
With Map Viewer (formerly a separate beta installation but now included with the portal automatically), you can explore various styling options using smart mapping defaults. When you style map layers in Map Viewer, the nature of the data determines the styling options that appear by default in the Styles pane. You can then experiment with color ramps, line weights, transparency, symbols, and other graphic elements, and see your choices reflected immediately on the map.
Apply a style
The styling options provided for a layer are based on the type of data you are mapping. The available options depend on whether the layer is composed of point, line, or polygon features. For example, heat map styling options are available for a layer composed of points, but not for line or polygon layers. The options are also influenced by the type of data associated with the features. For example, a point feature may only have location information such as geographic coordinates but may also have categorical information such as tree species or numerical information such as air temperature. Not every styling option can be used for every type of data. By analyzing these and other characteristics of the data, Map Viewer presents the best styling options.
You can create a custom expression written in the ArcGIS Arcade scripting language to use for styling instead of styling a feature layer using explicit attributes in the layer. This is available for most styles. For example, you can create an Arcade expression to derive a yearly sales figure for individual sales territories by summing the value of monthly sales fields. The yearly sales figures can then be represented as different-sized symbols on the map. You can also create an Arcade expression or edit an existing Arcade expression directly in Map Viewer. You can also use Arcade expressions when setting transparency for features or the rotation angle of symbols.
When you add a layer without any styling attached to it—for example, you add a hosted feature or imagery layer from its item page immediately after publishing—Map Viewer displays the layer with default styling applied. If you add a layer with existing styling applied, Map Viewer respects that styling. You can change the style of a supported layer at any time by clicking the Styles button on the Settings toolbar.
To apply a style or change the style of a feature layer, do the following:
- Confirm that you are signed in and, if you want to save your changes, that you have privileges to create content.
- In Map Viewer, open the map containing the layer or add the layer directly.
- In the Layers pane, click the layer to select it.
- On the Settings (light) toolbar, click Styles .
- In the Styles pane, do one of the following in the Choose attributes section:
- Click Field, find and select the attribute, and click Add to style an attribute in the layer.
- Click Expression and create a custom Arcade expression in the editor window, including providing a name, to style the layer.
You can also use existing expressions to build new expressions; however, some variables may not work in all profiles—for example, an expression created for pop-ups may not work for styles. To use an existing expression, select it from the Existing tab in the editor window.
If you need help with any of the Arcade functions, click Information next to the function in the editor window to see reference information about it.
- To style additional attributes or create more expressions, repeat the previous step.
The style currently applied to the layer is selected in the Try a drawing style section.
- Optionally, select a different style. Choose a style based on what you want to show.
For help choosing a style, see the Styles quick reference table.
Only the options that apply to the data appear. For example, if you only know the location of a feature, you can only use a single symbol or heat map, not size or color. However, if you have categorical or numeric information attached to those locations, smart mapping presents additional styling options.
Some styles also include a Theme option. Themes allow you to experiment with various views of your data. The availability of themes depends on the smart mapping style you choose.
- Optionally, click Style options on the style card to customize the look of the layer.
With Color and Size, Types and Size, Predominant Category and Size, Relationship and Size, Types and Size (age), and Color and Size (age), you apply styling options to each attribute. For example, if you choose the Types and Size style, choose options for Types (unique symbols) and Counts and Amounts (size).
- In the Style options pane, click Done when you finish customizing your style, or click Cancel to return to the Styles pane without saving your choices.
- In the Styles pane, click Done.
- On the Contents (dark) toolbar, click Save and open and click Save to save your styling changes to the map.
Styles quick reference
When you style a layer using smart mapping, the available styling options depend on the type of data you are mapping (point, line, polygon, or imagery) as well as the type of data attributes (numbers, categories, dates, and so on) and number of attributes you choose. Each style helps you tell a slightly different story and answer different questions with the data.
The following table provides a quick reference of the smart mapping styling options available for various types of data and some of the key questions you can answer using each style:
|Questions that smart mapping can answer
|Available smart mapping style
Examples: city service requests in Miami, white shark locations near New Zealand
One numeric attribute
Examples: above- and below-average childhood obesity rates, market value of parcels, annual average daily traffic
Two numeric attributes
Examples: number and rate of single-parent households, unemployment trend, richness and rarity of species
Three numeric attributes
Example: funding for conservation and wetlands programs, farming programs, and total funding
One or more numeric attributes (counts or amounts) with the same unit of measurement
Examples: distribution of various types of crime, distribution of unsheltered versus sheltered people who are homeless, distribution of population by race across the United States
Two to ten related numeric attributes with the same unit of measurement
Examples: predominant ethnic population per census tract, predominant housing type by census tract and which tracts have the highest and lowest total housing units
One category/type attribute
Example: wind turbines by manufacturer
One category/type and one numeric attribute
Example: unemployed people by county
One date/time attribute
Examples: Rotterdam buildings built or rebuilt after the Rotterdam Blitz, oldest buildings in Rotterdam, emergency incident response times, age of code violation from complaint to compliance date, sewer lines by installation year
Two date/time attributes
Examples: relationship between the age of storm water structures and inspection dates, relationship between the age of code violation (how long between complaint and compliance) and how recently the violations occurred
One date/time attribute and one numeric attribute
Example: most recent traffic accidents involving multiple cars, age of storm water structure inspections
One date/time attribute and one category/type attribute
Example: sewer lines by type and number of years since installation
Example: land cover including forest, urban, and agriculture
Examples: multiband Landsat imagery, high to low elevation
Continuous raster or imagery
Examples: United States temperatures, elevation in Iceland
Example: Soil map with legend
Multidimensional Vector Field