Advanced RChapter 5R4DS Reading Group1 / 10

CONTROL FLOWif
ifelse
case_when
switch
for
while
repeat
2 / 10

But First... BEER!State (abbreviated)
Year
Barrels (barrels produced)
Type (On premise, Bottles/Cans, Kegs/Barrels)

 
    state 
    year 
    barrels 
    type 
  


    AK 
    2008 
    2067.69 
    On Premises 
  

    AK 
    2009 
    2263.65 
    On Premises 
  

    AK 
    2010 
    1929.15 
    On Premises 
  

    AK 
    2011 
    2251.02 
    On Premises 
  

    AK 
    2012 
    2312.43 
    On Premises 
  

    AK 
    2013 
    2155.60 
    On Premises 
  

3 / 10

state	year	barrels	type
AK	2008	2067.69	On Premises
AK	2009	2263.65	On Premises
AK	2010	1929.15	On Premises
AK	2011	2251.02	On Premises
AK	2012	2312.43	On Premises
AK	2013	2155.60	On Premises

If and ifelse

Let's see if a random state in our dataset is my home town, NV

IF

if (sample(beer_states$state, 1) == "NV") print("My Home State")

IF ELSE

if (sample(beer_states$state, 1) == "NV") print("My Home State") else print("Not my home")

## [1] "Not my home"

IFELSE

ifelse((sample(beer_states$state, 1) == "NV"), print("My Home State"), print("Not my home"))

## [1] "Not my home"

## [1] "Not my home"

Why does the ifelse statement print "Not my home" twice?

4 / 10

CASE WHEN

Let's change the barrels column to categorical

beer_states %>%
  mutate(
    barrel_cat = 
      if (barrels >= 100000000) { 
        "A lot" 
      } else if (barrels >= 10000000) {
        "Many"
      } else if (barrels >= 1000000) {
        "A few"
      } else {
        "Not much"
      }
    )

beer_states %>%
  mutate(
    barrel_cat = case_when(
      barrels >= 100000000 ~ "A LOT!",
      barrels >= 10000000 ~ "Many",
      barrels >= 1000000 ~ "A few",
      TRUE ~ "Not much"
    )
  )

barrel_cat	n
A LOT!	12
Many	98
Not much	1569
A few	193

5 / 10

SWITCH

Let's make a small shiny app to see the number of barrels per state

library(shiny)
library(tidyverse)
brewing_materials <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-03-31/brewing_materials.csv')
beer_taxed <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-03-31/beer_taxed.csv')
brewer_size <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-03-31/brewer_size.csv')
beer_states <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-03-31/beer_states.csv')
ui <- fluidPage(
    sidebarLayout(
        sidebarPanel(
            selectInput(inputId = "dataset",
                        label = "Choose a dataset:",
                        choices = c("materials", "size", "states", "taxed"))
        ),
        mainPanel(
            verbatimTextOutput("summary")
        )
    )
)
server <- function(input, output) {
    datasetInput <- reactive({
        switch(input$dataset,
               "materials" = brewing_materials,
               "size" = brewer_size,
               "states" = beer_states,
               "taxed" = beer_taxed)
    })
    output$summary <- renderPrint({
        dataset <- datasetInput()
        summary(dataset)
    })
}
shinyApp(ui = ui, server = server)

runApp("Presentations/Week5/switch_app/app.R", display.mode = "showcase")

6 / 10

FOR

Create a "region" column based on each observatation's state

for (i in 1:nrow(beer_states)) {
  if (beer_states$state[i] %in% Region1) {
    beer_states$region[i] <- "Region 1"
  } else if (beer_states$state[i] %in% Region2) {
   beer_states$region[i] <- "Region 2"
  } else if (beer_states$state[i] %in% Region3) {
    beer_states$region[i] <- "Region 3"
  } else if (beer_states$state[i] %in% Region4) {
    beer_states$region[i] <- "Region 4"
  } else if (beer_states$state[i] %in% Region5) {
     beer_states$region[i] <- "Region 5"
  } else if (beer_states$state[i] %in% Region6) {
     beer_states$region[i] <- "Region 6"
  } else if (beer_states$state[i] %in% Region7) {
    beer_states$region[i] <- "Region 7"
  } else if (beer_states$state[i] %in% Region8) {
    beer_states$region[i] <- "Region 8"
  } else if (beer_states$state[i] %in% Region9) {
    beer_states$region[i] <- "Region 9"
  } else if (beer_states$state[i] %in% Region10) {
    beer_states$region[i] <- "Region 10"
  } else {
    beer_states$region[i] <- "Missing"
  }
}

7 / 10

WHILE

library(shiny)
beer_states <- readr::read_csv('https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-03-31/beer_states.csv')
ui <- fluidPage(
    sidebarPanel(numericInput('xqty', 'Number of States', 3, 1, 10)),
    mainPanel(tableOutput("while_debug")))
server <- function(input, output, session) {
   states <- unique(beer_states$state)
   my_vector <- reactive({
        i <- 0
        my_vector <- vector()
        while (i <= input$xqty) {
            my_vector[i] <- i
            i = i+1
        }
        return(my_vector)
    })
    output$while_debug <- renderTable({
        beer_states %>%
            filter(state %in% unique(beer_states$state)[my_vector()]) %>%
            filter(state != "total") %>%
            group_by(state) %>%
            summarise(num_barrels = sum(barrels))
    })
}  
shinyApp(ui = ui, server = server)

8 / 10

REPEAT

Let's revist beer in Nevada - rather than take one sample, we can use repeat to continue sampling until we find beer!

repeat {   
  if (sample(beer_states$state, 1) == "NV") {
    print("Go grab a beer!");
    break
  } else print("Maya doesn't live here");
}

[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Maya doesn't live here"
[1] "Go grab a beer!"

9 / 10

ALL TOGETHER!

This diagram is incomplete - let's improve it together!

10 / 10

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