And finally, for those that are extremely obsessive when it comes to their visualizations, we can use the tweenr package to create beautiful smooth plots. Grid graphics are the foundation on which ggplot2 is built. In the examples below, we will explore some of the features of the grid package. The package was developed by Paul Murell to overcome some of the deficiencies base R plotting functions. There are two components to grid graphics: graphic output, and viewports.
Graphical oututs are controlled with the grid. Grobs , or Graphical Objects, are the object forms of the graphical outputs found in plots. A useful but not very popular plot that can take the place of a boxplot. It has three essential parts:.
We can compute the data for a bagplot and plot one using the aplpack package. The alpack package makes it easy to create this bagplot with the built-in function. If were to make this plot using ggplot2, we could make three separate geom layers as in this example:. The plot above is a good starting point, but we can do better.
In the process, we will learn how to use the ggproto function which can be used to make any new layer you can think of and ultimately build your own plots. Next we need to plug our ggproto objects into a ggplot function with a custom layer that will plot the bagplot. This custom function is flexible as well.
Kahle and H. The R Journal, 5 1 , This is the final part of the series on data visualization using the popular ggplot2 package. Part 3 In part 1 of this series, we explored the fundamentals of ggplot2. Call: density. Time-Series [, ] from to Class 'dist' atomic [] Error in download. Error in ggmap houston : object 'houston' not found.
Note the ggmap package is no longer used in this lesson to generate a basemap, due changes in the way that maps are served from Google, but the data used in this tutorial are contained in the ggmap package. There are many ways to compute densities, and if the mechanics of density estimation are important for your application, it is worth investigating packages that specialize in point pattern analysis e.
In this case, we alter the argument h , which is a bandwidth parameter related to the spatial range or smoothness of the density estimate. Because of this, users must specify spatial coordinates for the center of the map which the code does anyways, making the location argument unnecessary. Google no longer requires an API, so that argument is removed from the function.
I haven't found a replacement, so it is commented out. You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. I had trouble reproducing the Houston Crime Maps from.
And the file 'HoustonCrime. The first step is to grab and plot the map which best represents the geographical extent of interest. This extent is portrayed in the figure below using the methods described above. It is this area we consider to be downtown Houston in this article. The stage is now set : we have the map from google maps and we have the crime data from the Houston Police Department which has been geocoded using Google Maps.
We can now combine the two in any way we want. Since these crimes are provided by the Houston Police Department by city block and later geocoded to the middle of the block, a significant amount of overplotting occurs.
Thus, the points are jittered to reduce the effects of overplotting. While we could use the alpha aesthetic for such a task, we stop short at the jittering because the alpha aesthetic diminishes the visibility of each of the points.
Since the points are being plotted on top of a fairly heterogeneous set of colored tiles, we need to enhance their visibility as much as possible. For this, a contour layer is used disregarding crime type. Each of these three correspond to locations commonly held by Houstonians to be particularly dangerous locations.
The lesser of these, near the intersection of Westheimer and Montrose, is known to have high rates of prostitution. The next most dangerous of these, near West Gray and Main, is known to be a criminal hotspot because of a Greyhound Lines bus station located there.
The most serious hotspot however is located to the north, around the intersection of Congress and Louisiana on the north side of downtown. This spot is less than half a mile five blocks or so from the county jail. Individuals are released from the jail daily at midnight and noon and tend to loiter in the nearby area. Contour plots can be difficult for untrained people to understand.
Fortunately, everyone is familiar with weather maps and what they mean. Thus, making weather maps to convey areas of heightened criminal activity can be preferable to the contour plot provided above.
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