R中使用Plotly和Shiny的交互式散点图

Question

我对 Shiny 和 Plotly 比较陌生，并且有以下代码 sn-p：

#
# This is a Shiny web application. You can run the application by clicking
# the 'Run App' button above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#

library(shiny)
library(plotly)
library(odbc)
library(DBI)



# Define UI for application that draws a histogram
ui <- fluidPage(

   # Application title
   titlePanel("Demo"),

   #Sidebar with a slider input for number of bins
   sidebarLayout(
      sidebarPanel(
         sliderInput("bins",
                     "Number of bins:",
                     min = 0,
                     max = 100,
                     value = 70)
      ),

      # Show a plot of the generated distribution
      mainPanel(
        tabPanel("Heading", plotlyOutput("tbTable"))

      )
   )
)

# Define server logic required to draw a histogram
server <- function(input, output, session) {

  QueriedData <- reactive({

    connn <- DBI::dbConnect(odbc::odbc(),.connection_string = "XXX", uid = "AB", pwd = "CD")
    lat_rec.df <- dbGetQuery(connn, "PQR")
    dbDisconnect(connn)
    lat_rec.df1
  })  


   output$tbTable <- renderPlotly({

     plot_ly(QueriedData(),x = ~TotalCount, y = ~MyScore, type = 'scatter', mode = 'markers')

  })

}

# Run the application 
shinyApp(ui = ui, server = server)

正如您在上面看到的，我正在绘制我从数据库中读取的数据帧的散点图（如反应函数中所述）。我有几个问题：

1. 我想使用滑动条输入作为我的 Y 轴 (MyScore)。我怎么做？我目前无法将滑块（箱）链接到我的绘图图中。我希望散点图根据滑块输入进行更新。
2. 我对反应函数有点困惑。这是否意味着每次我更改滑块时，数据库都会被调用（在反应函数中）？它是如何工作的？
3. 如果我有其他数据库表要读取和绘制在其他区域，我是否将其包含在反应函数中？请指教。

提前感谢您的帮助！干杯!

Answer 1

我对您三个问题的解决方案/答案。

1.如您想知道如何使用sliderInput控制Y轴，下面的代码解释了如何做到这一点。

library(shiny)
library(plotly)
library(DBI)
library(pool)

pool <- dbPool(drv = RMySQL::MySQL(),dbname = "db",host = "localhost",username = "root",password = "psw", port = 3306)
data <- dbGetQuery(pool, "SELECT * FROM testTable;")
ui <- fluidPage(
  titlePanel("Demo"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("bins", "Number of bins:", min = 0, max = 100, value = 70)
    ),
    mainPanel(
      tabPanel("Heading", plotlyOutput("tbTable"), 
               plotOutput("basicPlot") # Added extra as an Example for 3rd question
               )
    )
  )
)
server <- function(input, output, session) {
  QueriedData <- reactive({
    df <- data[data$total <= input$bins,] # filtering datafarme based on sliderInput
    return(df)
  })
  output$tbTable <- renderPlotly({
    plot_ly(QueriedData(), x = ~count, y = ~total, type = 'scatter', mode = 'markers')
  })
  # Added extra as an Example for 3rd question
  output$basicPlot <- renderPlot({
    data_for_plot <- dbGetQuery(pool, "SELECT * FROM dummyTable WHERE uid = 2018;")
    plot(x = data_for_plot$category, y = data_for_plot$performance, type = "p")
  })
}
shinyApp(ui = ui, server = server)

2.对于反应性，最好将表一次提取到数据帧中，然后将该数据帧放入反应性环境中。这样就可以避免多次数据库调用。您可以检查上面的代码。

3.reactive 环境的使用完全取决于您想要与闪亮的应用程序进行交互时的要求。如果您想从其他表中获取数据并在不同的图中使用，则无需将您的数据库连接字符串放置在响应式环境中。只需根据您的要求查询数据库，如上面的代码。