R Tutorial: Case Studies: Building Web Applications with Shiny in R | Inputs and outputs

Want to learn more? Take the full course at https://learn.datacamp.com/courses/case-studies-building-web-applications-with-shiny-in-r at your own pace. More than a video, you'll learn hands-on coding & quickly apply skills to your daily work. --- So far, you've reviewed how to create a Shiny app and add text to it. You might be thinking that this isn't very useful as a web application—it's more of a text document. In order to be useful, Shiny apps need inputs and outputs. Inputs are what gives users a way to interact with a Shiny app. An input is anything that the user can interact with, using the mouse or keyboard, to modify its value. For example, this is a text input, where users can enter text, and this is a numeric input, which lets users select a number. In fact, Shiny provides many different input functions, some of which, are shown here. Inputs are created by calling an input function inside the UI. Here is the code that creates the two inputs that you saw earlier. You may notice that the code for the two inputs has some similarities. Most input functions have the word "Input" in their name and have the same first two arguments: inputId and label. The inputId has to be unique, because later on you'll use this ID to retrieve the value of the input. The label argument is the descriptive text that appears above the input. Some inputs can also have other arguments specific to that input type, which we'll see later on. Outputs can be any object that R creates and that we want to display in our app - such as a plot, a table, or even just text. Creating an output, for example, a plot, is a two-step process. First you need to tell Shiny where to place the plot by adding an output placeholder in the UI. Similar to input functions, output placeholder functions also have an outputId parameter that must be unique. The second step is to actually write the R code for the plot. This is done in the server. So far we only wrote code in the UI - creating inputs and