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  3. Case Studies: Building Web Applications with Shiny in R

Exercise

Constructing output objects

There are three rules to build an output in Shiny:

  1. Build the object with the appropriate render*() function.

  2. Save the result of the render function into the output list, which is a parameter of the server function. Specifically, save it into output$<outputId> in order to replace the output placeholder in the UI that has ID outputId.

  3. If the output relies on any user-modified input values, you can access any of the inputs using the input parameter of the server function. Specifically, input$<inputId> will always return the current value of the input field that has ID inputId.

Instructions

100 XP

You are given a Shiny app with a fully functional UI portion. Your task is to construct all the outputs. Specifically:

  • Create a plot of the cars dataset in the plot output placeholder with ID "cars_plot" (line 23).
  • In the "greeting" text output, render a text greeting in the form of "Hello NAME", where NAME is the value of the name input (line 28).
  • In the "iris_table" output, show a table of the first n rows of the iris dataset, where n is the value of the numeric input (line 33).