R Shiny ggplot 对 varSelectInput 有反应

Question

我正在尝试找出如何使 ggplot 输出对我 Shiny 应用程序的 UI 中的 varSelectInput 函数作出 react 。例如，我希望能够选择两个不同的变量并将它们绘制为彼此的函数。我在这个例子中使用了航类数据集，即选择 arr_time 和 dep_delay 并查看 x 轴上的 arr_time 和 y 轴上的 dep_delay。

DateRangeInput 目前没有功能，但我最终希望能够按月筛选出在 ggplot 输出中绘制的结果。

library(tidyverse)
library(shiny)
flights <- nycflights13::flights

# Define UI for application
ui <- navbarPage(
    "NYC Flights",

    tabPanel(
        "Flights",
        sidebarPanel(
            h4("Flight Inputs"),
            selectInput(
                "Airline_Select",
                label = "Select Airline",
                choices = flights$Carrier,
                selected = TRUE
            ),
            dateRangeInput(
                "dates",
                label = "Dates",
                start = min(flights$Month),
                end = max(flights$Month),
                min = min(flights$Month),
                max = max(flights$Month)
            ),
            varSelectInput(
                "X_Axis",
                label = "Select Variable 1",
                data = flights
            ),
            varSelectInput(
                "Y_Axis",
                label = "Select Variable 2",
                data = flights
            ),
        ),
    )
)

mainPanel(plotOutput("flights_plot"))


# Define server logic
server <- function(input, output) {

    output$flights_plot <- renderPlot({
        ggplot(data = flights, aes(x = input$X_Axis, y = input$Y_Axis)) + geom_point()
    })
}
# Run the application 
shinyApp(ui = ui, server = server)

Answer 1

欢迎来到 stackoverlfow。

为了拥有一个功能性的应用程序，您必须更改一些内容。我在这里总结了我所看到的事情，并将代码中的详细信息作为注释。

1. 准备好你的数据，你应该考虑创建变量
2. 不要将具有重复值的整个向量作为 choices 参数放入 selectInput 中，您应该传递不同的选项。
3. 最好尽可能选择一个值。这样一来，您的应用将在启动时默认显示一些内容。
4. 使用输入来过滤数据。
5. selectInput 创建一个字符串值，为此，您应该在 ggplot mapping 参数中使用 aes_string。

library(shiny)
library(tidyverse)


# You have to Adequate your data: You have to create a dete variable
# in order to make the `dateRangeInput` work. You can do that using
# `year`, `month` and `day` variables as follow.
flights <- nycflights13::flights %>% 
    mutate(
        date = as.Date(paste(year, month, day, sep = "-"))
    )

ui <- navbarPage(
    title = "NYC Flights",
    tabPanel(
        title = "Flights",
        sidebarPanel(
            h4("Flight Inputs"),
            # The choices argument should be the unique
            # list of arilines, not the whole vector with
            # duplicates
            selectInput(
                "airline",
                label = "Select Airline",
                choices = unique(flights$carrier), 
                selected = 'UA' # It is a good idea to select a value
                # visible when you launch the app
            ),
            dateRangeInput(
                "dates",
                label = "Dates",
                start = min(flights$date),
                end = max(flights$date)
                ),
            varSelectInput(
                "X_Axis",
                label = "Select Variable 1",
                data = flights,
                selected = "date" # selecting one
            ),
            varSelectInput(
                "Y_Axis",
                label = "Select Variable 2",
                data = flights,
                selected = "dep_delay" # selecting one
            )
        ),

        mainPanel(
            plotOutput("plot")
        )

    )

)

server <- function(input, output, session) {

    output$plot <- renderPlot({
        flights %>% 
            # Use your inputs to filter the data
            filter(date >= input$dates[1], date <= input$dates[2], carrier == input$airline) %>% 
            # since the selectImput create a character element, you should use 
            # ase_string() to map the x an y variables
            ggplot(aes_string(x = input$X_Axis, y = input$Y_Axis)) +
            geom_point()
    })

}

shinyApp(ui, server)