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Below is the 4th exercise in book Mastering Shiny, Chapter 4: Case study: ER injuries.
“Provide a way to step through every narrative systematically with forward and backward buttons.Advanced: Make the list of narratives “circular” so that advancing forward from the last narrative takes you to the first.”
Collin Berke provided a solution, where the %%
was used for the circular purpose. However, employing %%
is a little tricky in this exercise. Thus, I use if else
in both Next and Previous arrows. Here is the code.
library(shiny) library(ggplot2) library(vroom) library(tidyverse) # set your own directory setwd('../../../data') injuries <- vroom::vroom("neiss/injuries.tsv.gz") population <- vroom::vroom("neiss/population.tsv") products <- vroom::vroom("neiss/products.tsv") prod_codes <- setNames(products$prod_code, products$title) count_top <- function(df, var, n = 5) { df %>% mutate({{ var }} := fct_lump(fct_infreq({{ var }}), n = n)) %>% group_by({{ var }}) %>% summarise(n = as.integer(sum(weight))) } ui <- fluidPage( fluidRow( column(8, selectInput("code", "Product", choices = setNames(products$prod_code, products$title), width = "100%" ) ), column(2, selectInput("y", "Y axis", c("rate", "count"))), column(2, numericInput("num_row", "Number of rows", 5, min = 1, max = 15)) ), fluidRow( column(4, tableOutput("diag")), column(4, tableOutput("body_part")), column(4, tableOutput("location")) ), fluidRow( column(12, plotOutput("age_sex")), ), fluidRow( column(2, span("Narrative Display:", style = "-weight: bold")), column(1, actionButton(inputId ="Previous", label = icon("arrow-left"))), column(1, actionButton(inputId ="Next", label = icon("arrow-right"))), column(8, textOutput("narrative")) ) ) server <- function(input, output, session) { # use the last 6 records to test narrative selected <- reactive(injuries %>% filter(prod_code == input$code) %>% slice_tail(n=6)) n_row <- reactive(input$num_row) # number of rows displayed in tables output$diag <- renderTable(count_top(selected(), diag, n = n_row()), width = "100%") output$body_part <- renderTable(count_top(selected(), body_part, n = n_row()), width = "100%") output$location <- renderTable(count_top(selected(), location, n = n_row()), width = "100%") summary <- reactive({ selected() %>% count(age, sex, wt = weight) %>% left_join(population, by = c("age", "sex")) %>% mutate(rate = n / population * 1e4) }) output$age_sex <- renderPlot({ if (input$y == "count") { summary() %>% ggplot(aes(age, n, colour = sex)) + geom_line() + labs(y = "Estimated number of injuries") } else { summary() %>% ggplot(aes(age, rate, colour = sex)) + geom_line(na.rm = TRUE) + labs(y = "Injuries per 10,000 people") } }, res = 96) ### narrative num_narr <- reactive( length(selected()$narrative) ) # a reactive value that can be easily changed later (in events) # ref: https://stackoverflow.com/questions/42183161/r-shiny-how-to-change-values-in-a-reactivevalues-object i <- reactiveValues(tmp=1) # reset i to 1 if code is changed by user # ref: https://www.collinberke.com/post/shiny-series-implementing-a-next-and-back-button/ observeEvent(input$code, { i$tmp <- 1 }) output$narrative <- renderText({ selected()$narrative[1] }) observeEvent(input$Next, { i$tmp <- i$tmp + 1 if(i$tmp <= num_narr()){ output$narrative <- renderText({ selected()$narrative[i$tmp] }) } else{ i$tmp <- 1 output$narrative <- renderText({ selected()$narrative[1] }) } }) observeEvent(input$Previous, { i$tmp <- i$tmp - 1 if(i$tmp > 0){ output$narrative <- renderText({ selected()$narrative[i$tmp] }) } else{ i$tmp <- num_narr() output$narrative <- renderText({ selected()$narrative[num_narr()] }) } }) } shinyApp(ui, server)
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