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Smart Mapping: Types (unique symbols)
Display your features by their category.
Sometimes it's enough to simply see the location of things, but other times you want to see locations by their category or type. If your data has an attribute field that captures a category, it's easy to map that field with a smart mapping drawing style called Types.
When working with your data in ArcGIS Online and Enterprise, choose the Styles option to work with smart mapping . Smart mapping helps you create beautiful and informative maps quickly. It suggests appropriate styles according to your attribute's field type. It you choose to map a string attribute, Types will be the suggested drawing style.
What is the Types style?
Public Universities in California
It's a style that simply creates a map in which each color or symbol represents a different category. The Types drawing style works for points, lines, and polygons.
For example, this map of public universities in California shows campuses as points, and the points are symbolized by system: the University of California system vs. the California State University system.
Florida Streets by District
Similarly, this map shows Florida streets as lines symbolized by which Florida Department of Transportation (FDOT) District in which it falls. Each district is a distinct category, and therefore has a distinct color: District 1, District 2, District 3, District 4, District 5, District 6, and District 7.
Home Owners' Loan Corporation (HOLC) Neighborhood Redlining Grade
An example of a categorical map containing polygons is this map of Historical Neighborhood Redlining Grades , a neighborhood ranking system created in the 1930s now infamously known as redlining. The grades ranged from A to D. A (Best) was traditionally colored in green, B (Still Desirable) was traditionally colored in blue, C (Declining) was traditionally colored in yellow, and D (Hazardous) was traditionally colored in red.
Use the Types style
Step 1: Select the Types style option
To start, load your layer with a categorized attribute into the Map Viewer with a neutral basemap to let your data shine.
Select your layer to symbolize, and open the Styles pane on the right toolbar.
Select the attribute you want to map.
Smart Mapping recognizes that this is a string field, and will start drawing a map using the Types style.
Click Style options.
In this example of Tribal Lands in the Dakotas, we can see that the Cheyenne River Sioux Tribe has two records.
Smart mapping tells you the frequency of each category in your attribute field, with the most frequent categories on top. According to the frequency counts on the side of the categories in the Style options panel, there are five categories here that have two records, whereas the others have one.
By default, we see the top ten categories mapped, and everything else gets grouped into "Other."
Click the arrows to the right of these categories to move them into the list in order for them to be symbolized using a unique color.
Now we see that all categories are symbolized by a unique color, and there are zero features in the Other group.
Uncheck the Other group since we don't need to display that on the legend.
Click the Symbol style editor to experiment with different colors.
You can even use your own colors by clicking on the color patch next to each of the categories in your list.
Your desired order that these categories show up in your legend might not be based on frequency.
Grab the six-pixel grid next to each category to drag and reorder as desired.
Consider re-applying the color ramp once you have re-ordered your categories.
I chose to order these Tribal Lands alphabetically in this map. The legend now reflects this.
Finally, you might want to modify a category's text. For example, I wanted to add the individual names of the Three Affiliated Tribes.
Click on the label in the list and type away! See your changes come through in the legend.
This example used the American Indian Reservations / Federally Recognized Tribal Entities layer in ArcGIS Living Atlas. Apply a filter to your state or region and try out this style for yourself.
Step 2: Apply your knowledge of the subject
Use your subject-matter expertise to make smart symbology choices. This can come through in your map's color and symbol choices.
For example, in this map of payday lending policies by state, notice the two legal categories (legal with limits on finance charges and legal with no limit on finance charges) are in different types of teal, and the illegal category is in a completely different color: yellow. The two legal categories are qualitatively closer together than the illegal category, hence the symbology choice here.
State Laws on Payday Lending
Optional: Consider adding size
Size can be a great way to enhance a map using the Types style. There are two ways to include size into your map: 1) you can edit each category's symbol by hand, applying a different size to each category, or 2) you can choose a numeric attribute to drive each feature's size across all categories.
This map of hospitals by Medicare quality score is an example of the first way to incorporate size. We emphasized the hospitals with a 5-star quality rating with an outline and a bigger size. Also, these categories have a natural order to the categories here: 1 star to 5 stars. Therefore, the colors also have a natural order to them. As a result, the map emphasizes the 5-star hospitals, but the 1-star hospitals are visible among all the others.
Hospital Overall Quality Rating
Alternatively, you could map two attributes at once: one using Types and one using Size.
This map of Florida streets by FDOT District uses size to show annual average daily traffic (depicted by the width of the line), as well as color to show the district. As a result, the highways pop and the minor streets are more subtle.
Florida Traffic
Experiment with different shapes, symbols, outlines, and sizes to enhance your map of categorical data. If you're limited with colors due to print or branding requirements, try using shape (e.g., squares vs. circles vs. triangles) to denote different categories. These little things can go a long way in bringing clarity to the data you are presenting through your map.
Last Step: Apply that final web map polish
- Are you using a basemap that doesn't compete with your map's features? The Gray Canvas and Human Geography basemaps are good choices and are available in Living Atlas .
- Is your legend clear? With the Types style, you can edit the text in your legend directly.
- Have you configured pop-ups in a way that communicates what you're mapping? Using a custom pop-up display allows for the greatest control.
- Are labels appropriate? Names of specific features can be helpful when zoomed in.
Try it out today, and when ready share your maps with the hashtag #smartmapping and #ArcGISOnline.