R Shiny运行报错object of type 'closure' is not subsettable求助

错误根因 #

1. UI结构定义存在语法错误：你在fluidPage内部再次对ui变量赋值navbarPage，导致Shiny解析UI结构时出现异常
2. 系数输出的响应式逻辑错误：output$coef_value使用renderUI时，内部嵌套了renderText，最终返回的是一个函数对象（closure类型），Shiny渲染UI时无法识别该类型对象，就会抛出object of type 'closure' is not subsettable报错

修正后完整代码 #

library(shiny)
library(shinythemes)
library(dplyr)
library(tidyverse)
library(lubridate)
library(stringr)

function.test<-function(){
  test <- structure(
    list(date1= c("2021-06-28","2021-06-28","2021-06-28","2021-06-28"),
         date2 = c("2021-07-01","2021-07-01","2021-07-02","2021-07-03"),
         Category = c("FDE","ABC","FDE","FDE"),
         Week= c("Friday","Monday","Wednesday","Wednesday"),
         DR1 = c(4,1,1,6),
         DR01 = c(4,1,1,3), DR02= c(4,2,2,4),DR03= c(9,5,5,2),
         DR04 = c(5,4,3,4),DR05 = c(5,4,2,4),
         DR06 = c(2,4,2,4),DR07 = c(2,5,4,2),
         DR08 = c(3,4,2,4),DR09 = c(2,3,4,2)),
    class = "data.frame", row.names = c(NA, -4L))
  return(test)
}

f1 <- function(test, dmda, CategoryChosse) {
  x<-test %>% select(starts_with("DR0"))
  x<-cbind(test, setNames(test$DR1 - x, paste0(names(x), "_PV")))
  PV<-select(x, date2,Week, Category, DR1, ends_with("PV"))
  med<-PV %>%
    group_by(Category,Week) %>%
    summarize(across(ends_with("PV"), median), .groups = "drop")
  SPV<-test%>%
    inner_join(med, by = c('Category', 'Week')) %>%
    mutate(across(matches("^DR0\\d+$"), ~.x + 
                    get(paste0(cur_column(), '_PV')),
                  .names = '{col}_{col}_PV')) %>%
    select(date1:Category, DR01_DR01_PV:last_col())
  SPV<-data.frame(SPV)
  
  mat1 <- test %>%
    filter(date2 == dmda, Category == CategoryChosse) %>%
    select(starts_with("DR0")) %>%
    pivot_longer(cols = everything()) %>%
    arrange(desc(row_number())) %>%
    mutate(cs = cumsum(value)) %>%
    filter(cs == 0) %>%
    pull(name)
  dropnames <- paste0(mat1,"_",mat1, "_PV")
  
  SPV <- SPV %>%
    filter(date2 == dmda, Category == CategoryChosse) %>%
    select(-any_of(dropnames))
  
  newdados<-SPV %>%
    filter(date2 == ymd(dmda)) %>%
    group_by(Category) %>%
    summarize(across(starts_with("DR0"), sum), .groups = "drop") %>%
    pivot_longer(cols= -Category, names_pattern = "DR0(.+)", values_to = "val") %>%
    mutate(name = readr::parse_number(name))
  colnames(newdados)[-1]<-c("Days","Numbers")
  
  if(as.Date(dmda) < min(as.Date(test$date1))){
    newdados <- newdados %>% 
      group_by(Category) %>% 
      slice(1:max(Days)+1) %>%
      ungroup
  }else{
    newdados <- newdados %>% 
      group_by(Category) %>% 
      slice((as.Date(dmda) - min(as.Date(test$date1) [
        test$Category == first(Category)])):max(Days)+1) %>%
      ungroup
  }
  
  plot(Numbers ~ Days,  xlim= c(0,45), ylim= c(0,30),
       xaxs='i',data = newdados,main = paste0(dmda, "-", CategoryChosse))
  
  model <- nls(Numbers ~ b1*Days^2+b2,start = list(b1 = 0,b2 = 0),data = newdados, algorithm = "port")
  
  new.newdados <- data.frame(Days = with(newdados, seq(min(Days),max(Days),len = 45)))
  new.newdados <- rbind(0, new.newdados)
  lines(new.newdados$Days,predict(model,newdata = new.newdados),lwd=2)
  coef_val<-coef(model)[2]
  points(0, coef_val, col="red",pch=19,cex = 2,xpd=TRUE)
  text(.99,coef_val + 1,max(0, round(coef_val,1)), cex=1.1,pos=4,offset =1,col="black")
  return(coef_val)
}

ui <- fluidPage(
  shiny::navbarPage(theme = shinytheme("flatly"), collapsible = TRUE,
                          br(),
                          tabPanel("",
                                   sidebarLayout(
                                     sidebarPanel(
                                       uiOutput("date"),
                                       uiOutput("mycode"),
                                       uiOutput("coef_value"),
                                       br(),
                                     ),
                                     mainPanel(
                                       tabsetPanel(
                                         tabPanel("", plotOutput("graph",width = "100%", height = "600")
                                         )
                                       ),
                                     ))
                          ))

server <- function(input, output,session) {
  mydados <- reactive(function.test())
  
  output$date <- renderUI({
    req(mydados())
    all_dates <- seq(as.Date('2021-01-01'), as.Date('2021-01-15'), by = "day")
    disabled <- as.Date(setdiff(all_dates, as.Date(mydados()$date2)), origin = "1970-01-01")
    dateInput(input = "date2", 
              label = h4("选择日期"),
              min = min(mydados()$date2),
              max = max(mydados()$date2),
              value = min(mydados()$date2),
              format = "dd-mm-yyyy",
              datesdisabled = disabled)
  })
  
  output$coef_value <- renderUI({
    req(input$date2,input$code)
    coef_val <- f1(mydados(),as.character(input$date2),as.character(input$code))
    tags$h4(paste("系数值为", round(coef_val, 1)))
  })
  
  output$mycode <- renderUI({
    req(input$date2)
    test <- mydados()
    test2 <- test[as.Date(test$date2) %in% input$date2,]
    selectInput("code", label = h4("选择分类"),choices=unique(test2$Category))
  })
  
  output$graph <- renderPlot({
    req(input$date2,input$code)
    f1(mydados(),as.character(input$date2),as.character(input$code))
  })
}

shinyApp(ui = ui, server = server)

内容的提问来源于stack exchange，提问作者Antonio