R 闪亮的 ggplot 响应 varSelectInput

Question

我正在尝试弄清楚如何使 ggplot 输出对我闪亮的应用程序的 UI 中的 varSelectInput 函数做出反应。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。我在本示例中使用了航班数据集，即选择 arr_time 和 dep_delay 并在 x 轴上查看 arr_time ，在 y 轴上查看 dep_delay 。

DateRangeInput 目前没有任何功能，但我最终希望能够过滤出 ggplot 输出中按月绘制的结果。

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

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

1. 准备数据，您应该考虑创建变量
2. 不要将具有重复值的整个向量作为choices参数放入 a 中selectInput，您应该传递不同的选项。
3. 尽可能选择一个值是个好主意。这样您的应用程序将启动并显示默认的内容。
4. 使用输入来过滤数据。
5. selectInput创建一个字符串值，因此，您应该aes_string在 ggplotmapping参数中使用。

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)