闪亮 - 如果没有使用滑块选择数据，如何防止绘图

Question

我想在我的Shiny应用程序中绘制一个标绘的3D图形，但仅限具有输入范围滑块范围内的值的数据。不过，我想阻止密谋当有滑块的范围内，没有价值观 - 目前这会导致以下错误，当没有输入：

Warning: Error in UseMethod: no applicable method for 'plotly_build' applied  
to an object of class "NULL" 

或示例代码：

Error in : length(Lab) == 3L is not TRUE 

这是有一个类似的错误作为原问题的一个示例代码：

library(shiny) 
library(plotly) 

d = diamonds[1:100,] 

ui = fluidPage(
headerPanel("Data"), 

sliderInput(inputId="slider", label = "Choose a range", value =c(0,max(d$price)), 
      min = 0,max = max(d$price)), 

# saves space for the plot in the user interface. Id allows communication 
plotlyOutput(outputId="trendPlot", width="100%", height=800) 

) 

server = function(input, output) 
{ 
NROF = reactiveValues(test = 1) 

output$trendPlot= renderPlotly({ 
d_sub=d[d$price >= input$slider[1] & d$price <= input$slider[2],] 
NROF = nrow(d) 
if(NROF != 0) 
{ 
    plot_ly(d_sub, x=d_sub$cut, y=d_sub$color, z=factor(d_sub$color), 
      type='scatter3d', mode='markers', 
      sizemode='diameter', size=d_sub$price, color=d_sub$price,colors = 'Set1') 

} 
}) 
} 

shinyApp(ui=ui, server=server) 

解决办法：我一直在使用抗值犯了一个错误 - 它应该是NROF $ TEST

Answer 1

听起来req()或validate()是你在找什么：

http://shiny.rstudio.com/articles/req.html

http://shiny.rstudio.com/articles/validation.html

library(shiny) 
library(plotly) 

d <- diamonds[1:100,] 

ui <- fluidPage(
    headerPanel("Data"), 
    sliderInput(inputId="slider", 
       label = "Choose a range", 
       value =c(0,max(d$price)), 
       min = 0,max = max(d$price)), 
    # saves space for the plot in the user interface. Id allows communication 
    plotlyOutput(outputId="trendPlot", 
       width="100%", height=800) 

) 

server <- function(input, output) { 
    output$trendPlot <- renderPlotly({ 
    d_sub <- d[d$price >= input$slider[1] & d$price <= input$slider[2],] 
    req(nrow(d_sub) > 0) 
    # validate(need(nrow(d_sub) > 0, "No data selected!")) 

    plot_ly(d_sub, x=d_sub$cut, y=d_sub$color, 
      z=factor(d_sub$color), type='scatter3d', 
      mode='markers', sizemode='diameter', 
      size=d_sub$price, color=d_sub$price, 
      colors = 'Set1') 
    }) 
} 

shinyApp(ui=ui, server=server) 

Answer 2

我试图重现它。我的建议是，有一个小的错字（你的意思是NROF = nrow(d_sub)而不是NROF = nrow(d)）。另外，您没有包含任何else案例的返回值。

这对你有帮助吗？

server = function(input, output) 
{ 
    NROF = reactiveValues(test = 1) 

    output$trendPlot= renderPlotly({ 
    d_sub=d[d$price >= input$slider[1] & d$price <= input$slider[2],] 
    NROF = nrow(d_sub) 
    if(NROF != 0) 
    { 
     plot_ly(d_sub, x=d_sub$cut, y=d_sub$color, z=factor(d_sub$color), 
       type='scatter3d', mode='markers', 
       sizemode='diameter', size=d_sub$price, color=d_sub$price,colors = 'Set1') 

    } else { 
     plot_ly(type='scatter3d') 
    } 
    }) 
}