R Tutorial: Setting the Default Map View

Key Takeaways

we have created several maps but you may have noticed that there's oom doubt rather than having to manually zoom the map to find the area that we're most interested in we can load it centered on a particular point with a specific zoom level let's take a closer look before we set the default view of our map we need to determine where we want our users to focus their attention once we select a location like data camps New York office we can use the geocode function from the gg map library to geocode an address or the name of a place we pass the geocode function a string containing an address like 350 5th Avenue New York and the function returns a coordinate pair that we can use to map the location taking a closer look at the geo code function and a few of its arguments we can use the loop location argument which takes a character vector containing an address or the name of a place the output argument that allows us to select how much information will be returned in the source argument which lets us select if we want to use the data science toolkit or Google to conduct the geocoding if you use Google you're agreeing to the Google Maps API Terms of Service and you should note that this API limits the number of queries you can run per day using this approach we can geo code place names like Colby College and setting the output argument to more will return the college's address in addition to its coordinates there are two common approaches to setting the default view of your map set view and fit bounds set view allows you to pick a single point at the centre of your map whereas fit bounds allows us to set the view based on a rectangle to use fit bounds we specify two diagonal corners of a rectangle I typically use set view as I find it easier to iterate through different possibilities using this approach sometimes we'll want our map to remain focused on a particular geographic area one way to accomplish this is to turn off the ability to pan the map and to limit the allowed soom levels switching dragging to false will prevent panning and setting the min and Max zoom arguments will limit the zoom range effectively setting and maintaining the focal point while preserving the interactive features of our web map we'll only use a small number of the available leaflet options in this course if you're interested in learning more about different options or features please visit our studio's leaflet for our guide and the reference guide on the leaflet JavaScript web site an alternative approach to keeping your Maps focus on a particular area is to use a set max bounds function instead of switching the dragging option to false if users try to pan your map outside of the max bounds they'll be automatically bounced back into the boundary let's get back to making our Maps