r - R Shiny 上的 ggplot，vs RStudio

Question

出于某种原因，“R Shiny”中的 ggplot 与 RStudio 中的普通 R 不同

可运行的 Shiny 代码是

library(ggplot2)
library(scales)
library(shiny)

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("Water Level" = "WaterLevel", 
                              "Discharge Debit" = "DischargeDebit"), 
                  selected = "WaterLevel"),

      selectInput(inputId = "z", 
                  label = "station:",
                  choices = c(
                    "NORTH SASKATCHEWAN RIVER NEAR DEER CREEK"="05EF001",
                    "BATTLE RIVER NEAR PONOKA"="05FA001",
                    "BATTLE RIVER AT DUHAMEL"="05FA011",
                    "PIGEON LAKE AT PIGEON LAKE PROVINCIAL PARK"="05FA013",
                    "MASKWA CREEK NO. 1 ABOVE BEARHILLS LAKE"="05FA014"
), 
selected = "05EF001")

    ),

    # Output
    mainPanel(
      plotOutput(outputId = "lineplot")
    )
  )
)



server <- function(input, output) {
file = "http://dd.weather.gc.ca/hydrometric/csv/SK/hourly/SK_hourly_hydrometric.csv"
skdat <- read.csv(file, head=T, sep=",", dec=".", stringsAsFactors = F)
colnames(skdat) <- c("ID", "Date", "WaterLevel", "Grade1", "Symbol1",
                     "QAQC-1", "DischargeDebit", "Grade2", "Symbol2",
                     "QAQC-2")

subds <- subset(skdat, ID=input$z)
subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H:%M:%OS")
output$lineplot <- renderPlot({ 
  ggplot(subds, aes(x = datetime, y = !!as.name(input$y))) + geom_line() 
})  


}

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

生成正确图形的 RStudio 代码是

library(ggplot2)
library(scales)
library(shiny)
library(stringi)



file = "http://dd.weather.gc.ca/hydrometric/csv/SK/hourly/SK_hourly_hydrometric.csv"
skdat <- read.csv(file, head=T, sep=",", dec=".", stringsAsFactors = F)
colnames(skdat) <- c("ID", "Date", "WaterLevel", "Grade1", "Symbol1",
                     "QAQC-1", "DischargeDebit", "Grade2", "Symbol2",
                     "QAQC-2")

subds <- subset(skdat, ID=='05EF001')
#subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H%m%S")
subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H:%M:%OS")#subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H%m%S-06:00")

p2 <- ggplot(subds, aes(x = datetime, y = WaterLevel)) + geom_line()
p2

Shiny 的代码中的渲染行一定有问题吗？

output$lineplot <- renderPlot({ 
  ggplot(subds, aes(x = datetime, y = !!as.name(input$y))) + geom_line() 
})

Shiny 图形显示为黑色 block ，看不到任何线条。 如有任何帮助，我们将不胜感激。

谢谢 jack !!这有助于下面的技巧

#subds <- subset(skdat, ID=input$z)
#subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H:%M:%OS")
#output$lineplot <- renderPlot({ 
#  ggplot(subds, aes(x = datetime, y = !!as.name(input$y))) + geom_line() 
#})  


output$lineplot <- renderPlot({
  subds <- subset(skdat, ID == input$z)
  subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H:%M:%OS")
  ggplot(subds, aes(x = datetime, y = !!as.name(input$y))) +
    geom_line()

Answer 1

在 RStudio 或 Shiny 中查看 ggplot2 图形没有区别。您用于制作两者的代码有差异。

1. 您的子集中没有逻辑语句(当您打算使用 == 时，您使用了 =)
2. 对于 1，您的数据集需要包装在 reactive
中
3. 虽然您可以使用 as.name，但如果您要使用完整的 tidyeval，您也可以使用 sym 的正确匹配。

下面的代码有效，但您可能想要在输入条件中检查要过滤的 ID。不确定这些是否会在以后添加，但它们不会按原样存在于您的数据中。

library(ggplot2)
library(scales)
library(shiny)

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("Water Level" = "WaterLevel", 
                              "Discharge Debit" = "DischargeDebit"), 
                  selected = "WaterLevel"),

      selectInput(inputId = "z", 
                  label = "station:",
                  choices = c(
                    "NORTH SASKATCHEWAN RIVER NEAR DEER CREEK"="05EF001",
                    "BATTLE RIVER NEAR PONOKA"="05FA001",
                    "BATTLE RIVER AT DUHAMEL"="05FA011",
                    "PIGEON LAKE AT PIGEON LAKE PROVINCIAL PARK"="05FA013",
                    "MASKWA CREEK NO. 1 ABOVE BEARHILLS LAKE"="05FA014"
                  ), 
                  selected = "05EF001")

    ),

    # Output
    mainPanel(
      plotOutput(outputId = "lineplot")
    )
  )
)



server <- function(input, output) {
  file = "http://dd.weather.gc.ca/hydrometric/csv/SK/hourly/SK_hourly_hydrometric.csv"
  skdat <- read.csv(file, head=T, sep=",", dec=".", stringsAsFactors = F)
  colnames(skdat) <- c("ID", "Date", "WaterLevel", "Grade1", "Symbol1",
                       "QAQC-1", "DischargeDebit", "Grade2", "Symbol2",
                       "QAQC-2")

  # Switched the date time to skdat from subds to not mess with reactivity until later
  skdat$datetime <- as.POSIXct(skdat$Date, format = "%Y-%m-%dT%H:%M:%OS")

  # You need to have a logical condition for subset, == not =
  subds <- reactive({subset(skdat, ID == input$z)})

  # Switched the use of as.name to rlang::sym 
  output$lineplot <- renderPlot({ 
    ggplot(subds(), aes(x = datetime, y = !!sym(input$y))) + geom_line() 
  })  


}

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