Rshiny Add user Inputs to List to generate plot/df

[Achrist]

I am using shiny to create app that allows user to enter locations which should go through some functions to pull data and be displayed on a table/graph. How can I adjust my code to either store previous user entries or add them to a list?

library('shiny')
library('shinythemes')
library('xlsx')
library("readxl")
library('xlsx')
library("tidyverse")
library("writexl")
library("covidcast")
library("dplyr")

#basic file loading

today=Sys.Date()
start_date=today - as.difftime(14,units = "days")
county_code=read_excel(choose.files())

#install.packages("covidcast_meta")

#define page layout
ui=fluidPage(
  #options(shiny.sanitize.errors=TRUE),
  theme=shinytheme("cerulean"),
  titlePanel("Covid Infection Rate Tracking App"),
  sidebarPanel(
  textInput(inputId ="user_state",label ="Please enter a state:eg. WA",),
  textInput(inputId ="user_county",label ="Please enter a county:eg. Benton",),
  submitButton("Update View", icon("refresh")),
  downloadButton("downloadPlot","Download Plot"),
  downloadButton("downloadData","Download Table"),
  
 
),
mainPanel(

  tabsetPanel(
    tabPanel(title = "Infection_Rate_Plot",plotOutput("line")),
    tabPanel(title="Data_Table", dataTableOutput("table"))
  ),
  
  #plotOutput("line"),
  #dataTableOutput("table")
),
hr(),
  print("The data displayed on this application is sourced from the Covidcast API.Infection rates cannot be displayed for a current day or for any locations that are not a part of the United States.")
)


#create output functions and insert source code
server <- function(input, output, session) {

  #####
  #####
 
    #### reactive is used to create a df from user entry which can be displayed.
  ######this serves as a function to run the background code and save it to a df
  #df_state=c("WA","WA")
  #df_county=c("Benton","Franklin")
  
      
  df=reactive({   
      #####test
      df_state=c("WA","WA")
      df_county=c("Benton","Franklin")
      df_state=append(df_state,input$user_state)
      df_county=append(df_county,input$user_county)
      ######
      l=length(df_county)#input$user_county)
      user_df=data.frame(matrix(ncol = 4, nrow = l)) 
      counter=1
      for (j in df_county){
        user=filter(county_code,State== df_state[counter] & Name== j)
        user_df[counter,]=user
        counter=counter+1
      }
      geo_code=sprintf("%05d",user_df$X2)
      user_df$X2=geo_code
      
      #data request
      Covidcast_data= suppressMessages(covidcast_signal(data_source = "jhu-csse",
                                                        signal = "confirmed_7dav_incidence_prop",start_day =start_date,
                                                        end_day = today,geo_type ="county",geo_values = geo_code))
      #data cleaning
      
      Test3 <-Covidcast_data%>%group_by(geo_value)%>% arrange(geo_value, time_value)
      Test3 <-Test3 %>% select(one_of("geo_value","time_value","value"))
      Test3$ID=user_df$X1[match(Test3$geo_value,user_df$X2)]
      Test3
})
    
    #using df() we display a reactive plot based on user input which was proccessed ABOVE
    my_plot=reactive({
      x=ggplot(df(),aes(x = time_value,y = value,color = ID))+
        geom_line()+ 
        geom_point()
      x + ggtitle("Plot of Covid Cases by Selected County per 100,000 people") +
        xlab("Time(days)") +
        ylab("Confirmed case per 100000") +theme_bw() + scale_x_date(date_breaks = "3 day")+
        theme(axis.text.x = element_text(angle = 90, vjust = 1, hjust=2))
    })   
      
    
    output$line=renderPlot({
      my_plot()
    })
    #####using df() we display a table based on user input proccessed above
    output$table=renderDataTable({
      df()
    })
    #######Download table
    output$downloadData <- downloadHandler(
      filename = function() {
        paste("Covid_Plot-", Sys.Date(), ".csv", sep="")
      },
      content = function(file) {
        write.csv(df(), file)
      }
    )
    #######Download Plot
    output$downloadPlot <- downloadHandler(
      filename = function() {
        paste("Infection_Rate_Graph-", Sys.Date(), ".png", sep="")
      },
      content = function(file) {
        png(file=file)
        plot(my_plot())
        dev.off()
      }
    )
  
}

shinyApp(ui=ui, server=server)

[Achrist]

What was changed in the code? What did I need to fix?

[nirgrahamuk]

If you need a common data store for many users to persist over multiple days, you will need to host a database that your application can read from and write to.
If you only need each user to see their previous stored info from the same continious session, (but not other users contributions, or the same users from a previously closed session) then you could do this with in memory objects, only slightly differently to how you would in a conventional non shiny script.

[Achrist]

Would you be able to provide an example of a memory object for shiny apps? I am not 100% versatile in rstudio or shiny.

[Achrist]

I only need the app to save the user input within the continuous session so I can use it to produce the correct outputs since the table/graph are based on all user inputs in the session.