From eb08882db327777bf68549f79dff21ca8c5e3b67 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9DAnFeliz=E2=80=9D?= <angel.esteban.feliz@gmail.com>
Date: Sat, 6 Apr 2024 12:25:47 -0400
Subject: [PATCH] solving exercises chapther 16

---
 .../16.3.4-exercises/01-exercise.R            | 29 +++++++++++++++
 .../16.3.4-exercises/02-exercise.R            | 28 +++++++++++++++
 .../16.3.4-exercises/03-exercise.R            | 35 +++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 examples/16-escaping_the_graph/16.3.4-exercises/01-exercise.R
 create mode 100644 examples/16-escaping_the_graph/16.3.4-exercises/02-exercise.R
 create mode 100644 examples/16-escaping_the_graph/16.3.4-exercises/03-exercise.R

diff --git a/examples/16-escaping_the_graph/16.3.4-exercises/01-exercise.R b/examples/16-escaping_the_graph/16.3.4-exercises/01-exercise.R
new file mode 100644
index 00000000..39d4a1ed
--- /dev/null
+++ b/examples/16-escaping_the_graph/16.3.4-exercises/01-exercise.R
@@ -0,0 +1,29 @@
+
+# Provide a server function that draws a histogram of 100 random numbers
+#  from a normal distribution when normal is clicked, and 100 random uniforms.
+
+library(shiny)
+
+ui <- fluidPage(
+  actionButton("rnorm", "Normal"),
+  actionButton("runif", "Uniform"),
+  plotOutput("plot")
+)
+
+server <- function(input, output, session) {
+  
+  values <- reactiveVal(vector(mode = "numeric"))
+  
+  observeEvent(input$rnorm, values(rnorm(100)))
+  
+  observeEvent(input$runif, values(runif(100)))
+  
+  output$plot <- renderPlot({
+    req(input$rnorm | input$runif)
+    hist(values())
+  })
+}
+
+shinyApp(ui, server)
+
+# source: https://mastering-shiny-solutions.netlify.app/escaping-the-graph
\ No newline at end of file
diff --git a/examples/16-escaping_the_graph/16.3.4-exercises/02-exercise.R b/examples/16-escaping_the_graph/16.3.4-exercises/02-exercise.R
new file mode 100644
index 00000000..ce1df7e4
--- /dev/null
+++ b/examples/16-escaping_the_graph/16.3.4-exercises/02-exercise.R
@@ -0,0 +1,28 @@
+
+# Modify your code from above for to work with this UI:
+
+library(shiny)
+
+ui <- fluidPage(
+  selectInput("type", "type", c("Normal", "Uniform")),
+  actionButton("go", "go"),
+  plotOutput("plot")
+)
+
+server <- function(input, output, session) {
+  
+  values <- reactiveVal(vector(mode = "numeric"))
+  
+  observeEvent(input$go, {
+    if(input$type == "Normal") values(rnorm(100)) else values(runif(100))
+  })
+  
+  output$plot <- renderPlot({
+    req(input$go)
+    hist(values())
+  })
+}
+
+shinyApp(ui, server)
+
+# source: https://mastering-shiny-solutions.netlify.app/escaping-the-graph
\ No newline at end of file
diff --git a/examples/16-escaping_the_graph/16.3.4-exercises/03-exercise.R b/examples/16-escaping_the_graph/16.3.4-exercises/03-exercise.R
new file mode 100644
index 00000000..b1c84266
--- /dev/null
+++ b/examples/16-escaping_the_graph/16.3.4-exercises/03-exercise.R
@@ -0,0 +1,35 @@
+
+# Rewrite your code from the previous answer to eliminate the use of 
+# observe()/observeEvent() and only use reactive().
+# Why can you do that for the second UI but not the first?
+
+# Now we just need to track the event go.
+
+library(shiny)
+
+ui <- fluidPage(
+  selectInput("type", "type", c("Normal", "Uniform")),
+  actionButton("go", "go"),
+  plotOutput("plot")
+)
+
+server <- function(input, output, session) {
+  
+  values <- reactive({
+    if(input$go == 0) return(NULL)
+    if(input$type == "Normal"){
+      rnorm(100)
+    }else{
+      runif(100)
+    }
+  })
+  
+  output$plot <- renderPlot({
+    if(is.null(values())) return(NULL)
+    hist(values())
+  })
+}
+
+shinyApp(ui, server)
+
+# source: https://mastering-shiny-solutions.netlify.app/escaping-the-graph
\ No newline at end of file