R Shiny - 如何使用 "melt" 函数（reshape2 包）创建堆叠条形图

Question

感谢您的回答，我设法制作了一个根据时间单位（周、月、年）做出反应并按时间单位汇总数据的条形图（link 在这里）：

然后，我想制作一个包含两个变量的堆叠条形图。为此，我生成了包含两个变量的后续数据框（即在我的示例中：Imported_cases 和 Autochthonous_cases），并应用了“melt”函数。 UI 在这里：

library(shiny)
library(dplyr)
library(lubridate)
library(ggplot2)
library(scales)
library(reshape2)

Disease <- data.frame(
  Date = seq(as.Date("2015/1/1"), as.Date("2017/1/1"), "days"),
  Imported_cases = rep(1),Autochtonous_cases=rep(2))
Disease <- Disease %>% mutate(
  Week = format(Date, "%Y-%m-%U"),
  Month = format(Date, "%Y-%m"), Year = format(Date, "%Y"))
Disease<- melt(Disease, id = c("Date","Week","Month","Year"), 
               measured = c("Imported_cases", "Autochtonous_cases"))
print(head(Disease))

ui <- fluidPage(
      dateRangeInput("daterange", "Choice the date",
                     start = min(Disease$Date),
                     end   = max(Disease$Date),
                     min   = min(Disease$Date),
                     max   = max(Disease$Date),
                     separator = " - ", format = "dd/mm/yy",
                     startview = 'Month', language = 'fr', weekstart = 1),
      selectInput(inputId = 'Time_unit',
                  label = 'Time_unit',
                  choices = c('Week', 'Month', 'Year'),
                  selected = 'Month'),
                  plotOutput("Disease"))

当我运行我的服务器时，R Shiny 显示：找不到错误对象 'variable'。您在服务器代码下方找到：

server <- function(input, output) {
dateRangeInput <- reactive({
dataset <- subset(
  Disease, Date >= input$daterange[1] & Date <= input$daterange[2])
dataset
})

selectInput = reactive({
dataset <- dateRangeInput() %>% group_by_(input$Time_unit) %>% 
  summarise(Sum = sum(value))
dataset
})

output$Disease <-renderPlot({
                ggplot(data=selectInput(), 
                aes_string(x = input$Time_unit, y = "Sum", 
                           fill = "variable"))  + 
                geom_bar(stat = "identity")
                })

}
shinyApp (ui = ui, server = server)

不知道是selectInput的代码问题还是output$Disease的代码问题。我不明白为什么Shiny找不到"variable"（cf.print(head(Disease)）。谢谢你的帮助（我希望清楚）。

Answer 1

下面是将要运行并创建堆积条形图的代码：

library(shiny) 
library(dplyr)
library(lubridate)
library(ggplot2)
library(scales)
library(reshape2)

Disease<-data.frame(Date=seq(as.Date("2015/1/1"), as.Date("2017/1/1"), "days"),Cases=rep(1),Autochtonous_cases=rep(2))
Disease <- Disease %>% mutate(Week = format(Date, "%Y-%m-%U"),Month = format(Date, "%Y-%m"), Year = format(Date, "%Y"))
Disease<-melt(Disease,id=c("Date","Week","Month","Year")) # just id


ui <- fluidPage(
  dateRangeInput("daterange", "Choice the date",
                 start = min(Disease$Date),
                 end = max(Disease$Date),
                 min = min(Disease$Date),
                 max = max(Disease$Date),
                 separator = " - ", format = "dd/mm/yy",
                 startview = 'Month', language = 'fr', weekstart = 1),
  selectInput(inputId = 'Time_unit',
              label='Time_unit',
              choices=c('Week','Month','Year'),
              selected='Month'),
  plotOutput("Disease"))


server <- function(input, output) {
  dateRangeInput<-reactive({
    dataset <- subset(Disease, Date >= input$daterange[1] & Date <= input$daterange[2])
    dataset
  })
  selectInput= reactive({
    dataset <- dateRangeInput() %>% group_by_(input$Time_unit,"variable") %>% summarise(Sum = sum(value)) #I have added here grouping as variable
    print(head(dataset))
    dataset
  })

  output$Disease <-renderPlot({
    ggplot(data=selectInput(), aes_string(x=input$Time_unit,y="Sum", fill = "variable"))  + geom_bar(stat="identity") + 
      labs(title="Disease", y ="Number of cases") +
      theme_classic() + 
      theme(plot.title = element_text(hjust = 0.5))
  })

}
shinyApp (ui = ui, server = server)

我想这就是您要找的。你在 melt 函数中有一些小错误，只设置 id 变量就足够了，第二件事是考虑在 group_by_ 中创建的变量列（因为你想获得案例和自动案例的计数），最后是在 ggplot 中使用变量作为 fill 参数。

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