Using multiple reactive values

Question

I am trying to create a shiny R application where the user inputs 2 dates: the start date and the end date(assuming that the user will choose either of the dates for a particular week).By choosing the dates the user will be able to see how much he will be selling each item from a list of items next week within those days. I have been provided with data on what percent of total sales happen each day within a week. Using that and using data on sales of each item from past week I have tried to create the app. However I think I am making some error while using the reactive expression. Any help will be greatly appreciated. I have provided the code below.

ui.R
library(shiny)
shinyUI(fluidPage(
  sidebarLayout(
    sidebarPanel(
      dateInput('Start_Date',label = "starting on:",value = Sys.Date())
      dateInput('End_Date',label = "Ending on:",value = Sys.Date())
    ),
    mainPanel(
      tableoutput("mytable")
      )
  )
  ))

server.R
library(shiny)
library(stats)
shinyServer(function(input, output) {
  Days<-c("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday")
  Percent_sales_by_day<-c(.10,.14,.14,.14,.14,.17,.17)
  Data_days<-data.frame(Days,Percent)
  items_sold<-c("A","B","C","D")
  sales_last_week<-c("100","200","300","800")
  Data_sales<-data.frame(items_sold,sales_last_week)
  Day_vector<-reactive({
    weekdays(seq(as.Date(input$Start_Date),as.Date(input$End_Date),by = "days")) 
  })
  Daily_split_vector<-reactive({
    library(dplyr)
    Data_days%>%
      filter(Days %in% Day_vector())
    Data_days$Percent_sales_by_day
  })
  Daily_split_value<-reactive({
    sum(Daily_split_vector())
  })
  Forecast<-reactive({
    Data_sales%>%
      mutate(sales_last_week=sales_last_week* Daily_split_value())
  })
  output$mytable<-renderTable({
    Forecast()
  })
  })

Answer 1

I'm not 100% clear on your underlying objective, but regardless the code below runs for me. I tried to comment all of the changes I made - they were mostly just minor syntactic errors - but let me know if you would like me to clarify anything.

---

ui.R:

library(shiny)
##
shinyUI(fluidPage(
  sidebarLayout(
    sidebarPanel(

      dateInput(
        'Start_Date',
        label = "starting on:",
        value = Sys.Date()
      ), ## added comma
      dateInput(
        'End_Date',
        label = "Ending on:",
        value = Sys.Date())
    ),

    mainPanel(
      tableOutput("mytable") ## 'tableOutput' not 'tableoutput'
    )

  )
))

---

server.R:

library(shiny)
library(dplyr)
options(stringsAsFactors=F)  ## try to avoid factors unless you
                             ## specifically need them
##
shinyServer(function(input, output) {

  Days <- c(
    "Sunday","Monday","Tuesday","Wednesday",
    "Thursday","Friday","Saturday")

  Percent_sales_by_day <- c(
    .10,.14,.14,.14,.14,.17,.17)

  Data_days <- data.frame(
    Days,
    Percent_sales_by_day) ## changed from 'Percent'

  items_sold <- c("A","B","C","D")

  sales_last_week <- c(
    100,200,300,800) ## changed from character (???) to numeric type

  Data_sales <- data.frame(
    items_sold,
    sales_last_week)

  Day_vector <- reactive({
    weekdays(
      seq.Date(
        as.Date(input$Start_Date),
        as.Date(input$End_Date),
        by = "day")) 
  })

  Daily_split_vector <- reactive({
    Data_days %>%
      filter(Days %in% Day_vector()) %>% ## added pipe
   ## Data_days$Percent_sales_by_day  ## changed this line
      select(Percent_sales_by_day)    ## to this line
  })

  Daily_split_value <- reactive({
    sum(Daily_split_vector())
  })

  Forecast <- reactive({
    Data_sales%>%
      mutate(
        sales_last_week=sales_last_week* Daily_split_value())
  })

  output$mytable <- renderTable({
    Forecast()
  })
})