学习笔记：Building Web Applications in R with Shiny 学习笔记

• Building Web Applications in R with Shiny 做app，需求也很强，必须搞啊！ 这些东西就是入门慢。

• 4 hours

• 17 Videos

• 55 Exercises

• 1,129 Participants 说明了问题，学习的人很少。

Mine Cetinkaya-Rundel | DataCamp 她教的， 她有很多课。

• Welcome to the course! | R

selected是default值设计。

library(shiny)
library(ggplot2)
load(url("http://s3.amazonaws.com/assets.datacamp.com/production/course_4850/datasets/movies.Rdata"))

# Define UI for application that plots features of movies 
ui <- fluidPage(
  
  # Sidebar layout with a input and output definitions 
  sidebarLayout(
    
    # Inputs
    sidebarPanel(
      
      # Select variable for y-axis
      selectInput(inputId = "y", 
                  label = "Y-axis:",
                  choices = c("imdb_rating", "imdb_num_votes", "critics_score", "audience_score", "runtime"), 
                  selected = "imdb_rating"),
      # Select variable for x-axis
      selectInput(inputId = "x", 
                  label = "X-axis:",
                  choices = c("imdb_rating", "imdb_num_votes", "critics_score", "audience_score", "runtime"), 
                  selected = "imdb_num_votes")
    ),
    
    # Outputs
    mainPanel(
      plotOutput(outputId = "scatterplot")
    )
  )
)

# Define server function required to create the scatterplot
server <- function(input, output) {

  # Create scatterplot object the plotOutput function is expecting
  output$scatterplot <- renderPlot({
    ggplot(data = movies, aes_string(x = input$x, y = input$y)) +
      geom_point()
  })
}

# Create a Shiny app object
shinyApp(ui = ui, server = server)

• Extend the UI | R

selectInput就是input框的选择框。 其中， inputId是用于画图的识别id。 新增一个selectInput。

library(shiny)
library(ggplot2)
load(url("http://s3.amazonaws.com/assets.datacamp.com/production/course_4850/datasets/movies.Rdata"))

# Define UI for application that plots features of movies
ui <- fluidPage(
  
  # Sidebar layout with a input and output definitions
  sidebarLayout(
    
    # Inputs
    sidebarPanel(
      
      # Select variable for y-axis
      selectInput(inputId = "y", 
                  label = "Y-axis:",
                  choices = c("imdb_rating", "imdb_num_votes", "critics_score", "audience_score", "runtime"), 
                  selected = "audience_score"),
      
      # Select variable for x-axis
      selectInput(inputId = "x", 
                  label = "X-axis:",
                  choices = c("imdb_rating", "imdb_num_votes", "critics_score", "audience_score", "runtime"), 
                  selected = "critics_score"),
      
      # Select variable for color
      selectInput(inputId = "z", 
                  label = "Color by:",
                  choices = c("title_type", "genre", "mpaa_rating", "critics_rating", "audience_rating"),
                  selected = "mpaa_rating")
    ),
    
    # Outputs
    mainPanel(
      plotOutput(outputId = "scatterplot")
    )
  )
)

# Define server function required to create the scatterplot
server <- function(input, output) {
  
  # Create the scatterplot object the plotOutput function is expecting
  output$scatterplot <- renderPlot({
    ggplot(data = movies, aes_string(x = input$x, y = input$y,
                                     color = input$z)) +
      geom_point()
  })
}

# Create a Shiny app object
shinyApp(ui = ui, server = server)

• Extend the UI further | R

在choices中， 修改label名字，很重要，因为有时候体现的时候，要展示中文。

library(shiny)
library(ggplot2)
load(url("http://s3.amazonaws.com/assets.datacamp.com/production/course_4850/datasets/movies.Rdata"))

# Define UI for application that plots features of movies
ui <- fluidPage(
  
  # Sidebar layout with a input and output definitions
  sidebarLayout(
    
    # Inputs
    sidebarPanel(
      
      # Select variable for y-axis
      selectInput(inputId = "y", 
                  label = "Y-axis:",
                  choices = c("IMDB rating" = "imdb_rating", 
                              "IMDB number of votes" = "imdb_num_votes", 
                              "Critics score" = "critics_score", 
                              "Audience score" = "audience_score", 
                              "Runtime" = "runtime"), 
                  selected = "audience_score"),
      
      # Select variable for x-axis
      selectInput(inputId = "x", 
                  label = "X-axis:",
                  choices = c("IMDB rating" = "imdb_rating", 
                              "IMDB number of votes" = "imdb_num_votes", 
                              "Critics score" = "critics_score", 
                              "Audience score" = "audience_score", 
                              "Runtime" = "runtime"), 
                  selected = "critics_score"),
      
      # Select variable for color
      selectInput(inputId = "z",
                  label = "Color by:",
                  choice = c("Title type" = "title_type",
                             "Genre" = "genre",
                             "MPAA rating" = "mpaa_rating",
                             "Critics rating" = "critics_rating",
                             "Audience rating" = "audience_rating"),
                  selected = "mpaa_rating"
                  )
    ),
    
    # Output
    mainPanel(
      plotOutput(outputId = "scatterplot")
    )
  )
)

# Define server function required to create the scatterplot
server <- function(input, output) {
  
  # Create the scatterplot object the plotOutput function is expecting
  output$scatterplot <- renderPlot({
    ggplot(data = movies, aes_string(x = input$x, y = input$y,
                                     color = input$z)) +
      geom_point()
  })
}

# Create a Shiny app object
shinyApp(ui = ui, server = server)

• Server function | R

我个人感觉， 前面fluidPage就是导入导出数据的， server是具体实现的function。

好听！

• Fix it up | R

library(shiny)
library(ggplot2)
load(url("http://s3.amazonaws.com/assets.datacamp.com/production/course_4850/datasets/movies.Rdata"))

# Define UI for application that plots features of movies
ui <- fluidPage(
  
  # Sidebar layout with a input and output definitions
  sidebarLayout(
    
    # Inputs
    sidebarPanel(
      
      # Select variable for y-axis
      selectInput(inputId = "y", 
                  label = "Y-axis:",
                  choices = c("IMDB rating"          = "imdb_rating", 
                              "IMDB number of votes" = "imdb_num_votes", 
                              "Critics score"        = "critics_score", 
                              "Audience score"       = "audience_score", 
                              "Runtime"              = "runtime"), 
                  selected = "audience_score"),
      
      # Select variable for x-axis
      selectInput(inputId = "x", 
                  label = "X-axis:",
                  choices = c("IMDB rating"          = "imdb_rating", 
                              "IMDB number of votes" = "imdb_num_votes", 
                              "Critics score"        = "critics_score", 
                              "Audience score"       = "audience_score", 
                              "Runtime"              = "runtime"), 
                  selected = "critics_score"),
      
      # Select variable for color
      selectInput(inputId = "z", 
                  label = "Color by:",
                  choices = c("Title type" = "title_type", 
                              "Genre" = "genre", 
                              "MPAA rating" = "mpaa_rating", 
                              "Critics rating" = "critics_rating", 
                              "Audience rating" = "audience_rating"),
                  selected = "mpaa_rating")
    ),
    
    # Outputs
    mainPanel(
      plotOutput(outputId = "scatterplot")
    )
  )
)

# Define server function required to create the scatterplot
server <- function(input, output) {
  
  # Create the scatterplot object the plotOutput function is expecting
  output$scatterplot <- renderPlot({
    ggplot(data = movies, aes_string(x = input$x, y = input$y,
                                     color = input$z)) +
      geom_point()
  })
}

# Create a Shiny app object
shinyApp(ui = ui, server = server)

• Reactive flow | R

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