Overlay Groups

1. Overlay Groups

In the next set of exercises, we'll practice building up our maps in layers and will use a new concept, groups, to give our users the ability to control which college sectors are displayed on the map.

2. Grouping Colleges by Sector

Let's take a look back at our map of California colleges to explore the idea of groups. When we map all of the sectors at once, our map gets pretty crowded. One approach to correct this is to plot each sector as a separate layer. To start, we can map public colleges by creating a subset of the IPEDS data that includes only public colleges in California. You'll notice that we are now using the group argument in addCircleMarkers(). This is how we will refer to the layers later in our code.

3. Grouping Colleges by Sector

We can then extend this idea to add private colleges. Building that layer with its own set of data. We can replicate the same logic a third time to add for-profit colleges. Based on what we’ve done so far, what do you think this code produces? This may seem like a bummer, but it simply gets us back to where we started with all three sectors cluttering up the map.

4. Grouping Colleges by Sector

To capitalize on the work we put in to create the groups, we need add the addLayersControl() function to the end of our chain of leaflet function calls. Passing our three overlay groups to this function will add a menu to our map that allows users to toggle which sectors are displayed.

5. What We are Working Toward

In the next set of exercises, you will apply this approach to create a map of American colleges with three marker layers. Users will be able to toggle the sectors of colleges displayed on your map. Take some time in the exercise to explore your map and to test out how the layer controls work. You'll notice that the order in which you add marker layers to your map matters, as they are stacked one on top of another.

6. Let's practice!

Now it is your turn to make this map. Keep up the great work!

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Interactive Maps with leaflet in R

BeginnerSkill Level

4.8+

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Chapter 1 will introduce students to the htmlwidgets package and the leaflet package. Following this introduction, students will build their first interactive web map using leaflet. Through the process of creating this first map students will be introduced to many of the core features of the leaflet package, including adding different map tiles, setting the center point and zoom level, plotting single points based on latitude and longitude coordinates, and storing leaflet maps as objects. Chapter 1 will conclude with students geocoding DataCamp’s headquarters, and creating a leaflet map that plots the headquarters and displays a popup describing the location.

Exercise 1: Introduction to leaflet Exercise 2: Loading the leaflet Library Exercise 3: Creating an Interactive Web Map Exercise 4: Map Tiles Exercise 5: Provider Tiles Exercise 6: Adding a Custom Map Tile Exercise 7: Setting the Default Map View Exercise 8: A Map with a View I Exercise 9: A Map with a Narrower View Exercise 10: Plotting DataCamp HQ Exercise 11: Mark it Exercise 12: Adding Popups and Storing your Map

In Chapter 4 students will learn to map polygons, which can be used to define geographic regions (e.g., zip codes, states, countries, etc.). Chapter 4 will start by plotting the zip codes in North Carolina that fall in the top quartile of mean family incomes. Students will learn to customize the polygons with color palettes and labels. Chapter 4 will conclude with adding a new layer to the map of every college in America that displays every zip code with a mean income of $200,000 or more during the 2015 tax year. Through the process of mapping zip codes students will learn about spatial data generally, geoJSON data, the @ symbol, and the addPolygons() function. Furthermore, students will have an opportunity to practice applying many of the options that they learned about in the previous chapters, such as popups and labels, as well as new ways to customize their maps, such as the highlight option in addPolygons().

Exercise 1: Spatial Data Exercise 2: Introduction to Spatial Data Exercise 3: Exploring Spatial Data Exercise 4: Joining Spatial Data Exercise 5: Mapping Polygons Exercise 6: addPolygons() Function Exercise 7: NC High Income Zips Exercise 8: addPolygon() Options Exercise 9: Let's do some Logging Exercise 10: Putting it All Together Exercise 11: Wealthiest Zip Codes in America Exercise 12: Final Map Exercise 13: Thank you!