In jr-packages/jrShiny: R Shiny Exercises

Exercise 18: interactive graphics

Open chapter5/interactive1.R and run.
- Using textOutput() and input$click, get the shiny app to print out the x and y coordinates of a user's click on the plot
- Change the output to display x and y to 4 significant figures.
- If you are familiar with ggplot2, change the base graphic plot to a ggplot2 scatter plot.
- Change the plot to a boxplot - does it still work?
Open chapter2/interactive2.R and run. Explore the other types of point selection.

Exercise 19: acting on interactive graphics

Open chapter5/interactive3.R and run.
In the nearPoints function, what does
- the argument threshold = 100 do?
- the argument maxpoints = 2 do?
- the argument allRows = TRUE do?
- the argument addDist = TRUE do?
When you click on a point, remove that point from the regression calculation and refit the line (this is quite hard!). I did this by using the allRows = TRUE argument.
- Add a reset button to your app
- Rather than clicking on a point, try brushing. See brushedPoints() for this.

Exercise 20: invalidating reactive contexts

Open chapter5/invalidate.R and run.
Can you change the app such that it produces a plot of movie ratings vs durations from a random sample of movies that changes every 5 seconds
Create a summary output of movie years, let this be it's own reactive context updating every 3 seconds from a random sample of movies.
Hard: Create a summary output of movie years, let this be it's own reactive context updating every 3 seconds by cycling through the movie genres.

This is a less guided exercise. The file below will give you some example code that you can play around with and modify to see what is going on. Feel free to try things with your own data.