Base Groups

1. Base Groups

Similar to how we added overlay groups, we can add base map groups to allow our users to toggle between different maps. Unlike overlay groups, only one base group may be selected at a time.

2. Base Groups and Multiple Map Tiles

To add multiple base groups, we need to call addProviderTiles() one time for each base map we want to make available to our users. For example, to add the OSM, CartoDB, and Esri tiles we could do the following. That's a nice map, but how do we change the base maps?

3. Base Groups and Multiple Map Tiles

Just like when adding multiple overlay groups, we need to include a call to addLayersControl() in our chain of functions to give our users the ability to toggle between different base maps. Otherwise, the last map tile that we add will be the only one that our users can see. That is a nice splash of color in the Esri map after using our greyscale map for most of the course. Let's use our new knowledge of base groups to take a look at all of the Esri map tiles that are available in the leaflet package.

4. Exploring Esri Base Maps

It can be handy to add a few base maps during an exploratory analysis to see how different markers appear on various map tiles. Using base groups, we can accomplish this with a single leaflet map, like this one that displays the 11 Esri provider tiles included in the leaflet package. Feel free to experiment with different map tiles while you are working on the exercises in this chapter.

5. Overlay and Base Groups

Putting all of these groups together takes a lot of code. Let's break it down into four steps. First, we initialize the leaflet htmlwidget. Then we add our three base maps with group names.

6. Overlay and Base Groups

Then we add one marker layer for each sector with a corresponding group name. For each marker layer, we also apply our color palette and add the label argument. Lastly, we add our layer controls so our users can toggle both the base groups and the overlay groups on a single map.

7. The Big Reveal

Here's the map we'll be making in the next set of exercises. In a relatively short period of time we have gone from mapping one state's colleges with a single color to creating a map of all American colleges that uses a color palette and provides several base and overlay groups.

8. Let's practice!

Now it's your turn. Keep up the great work!

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Interactive Maps with leaflet in R

BeginnerSkill Level

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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!