Added w2 lab code

week2/index.qmd

@@ -27,5 +27,13 @@ schedule |>
 ```{r}
 #| output: asis
 show_slides(week)
+```
+
+## Lab code
+
+Lab code can be downloaded here: [`week2_lab.R`](week2_lab.R)
+
+```{r}
+#| output: asis
 show_assignments(week)
 ```

week2/week2_lab.R

@@ -0,0 +1,193 @@
+FALSE == -1
+as.logical(-1)
+as.logical(NA)
+NA || TRUE
+
+list(1,2,3)[c(3,2,1)]
+
+letters[[1:5]]
+list(1,2,3)[[1]]
+
+
+lobstr::tree(list(list(3,2), 1, 4)[[1]])
+
+library(dplyr)
+as_tibble(mtcars)$mpg
+as_tibble(mtcars)$"mpg"
+
+as_tibble(mtcars)[["mpg"]]
+as_tibble(mtcars)["mpg"]
+
+as_tibble(mtcars)[[mpg]]
+
+
+
+as_tibble(mtcars)$mp
+mtcars$mp
+mtcars$mpz <- rnorm(nrow(mtcars))
+mtcars$mp
+
+
+matrix(rnorm(25), nrow = 5)[,1, drop = FALSE]
+matrix(rnorm(25), nrow = 5)[[5]]
+
+dim(matrix(rnorm(25), nrow = 5))
+attributes(matrix(rnorm(25), nrow = 5))
+
+
+ mat <- (matrix(rnorm(25), nrow = 5))
+c(mat)
+
+help("[[")
+?"[["
+?`[[`  
+
+
+
+mtcars[mtcars$cyl == 4, ]
+mtcars[-(1:4), ]
+mtcars[mtcars$cyl <= 5, ]
+mtcars[mtcars$cyl %in% c(4, 6), ]
+
+
+
+if (isTRUE(logy)) {
+  log(y)
+} else {
+  y
+}
+
+ifelse(mtcars$cyl <= 5, "small", "large")
+dplyr::if_else(mtcars$cyl <= 5, "small", "large")
+
+as_tibble(mtcars) |> 
+  mutate(
+    ifelse(mtcars$cyl <= 5, "small", "large")
+  )
+
+unclass(Sys.Date())
+
+ifelse(c(TRUE, FALSE), Sys.Date(), "Oops")
+dplyr::if_else(c(TRUE, FALSE), Sys.Date(), "Oops")
+dplyr::if_else(c(TRUE), Sys.Date(), NA)
+
+
+as.logical(length(1:10))
+as.logical(0)
+as.logical(-100)
+
+numeric()
+length(numeric())
+
+
+# Recycling makes this incorrect
+mtcars[mtcars$cyl == c(4, 6), ]
+
+
+length(mtcars$cyl)
+
+tibble(a = 1, b = 1:4)
+
+logplus1 <- function (x) {
+  x <- x + 1
+  if(logx) {
+    x <- log(x)
+  }
+
+  return(x)
+}
+
+body(logplus1)
+environment(logplus1) <- baseenv()
+
+logx <- TRUE
+logplus1(x = mtcars$cyl)
+
+x <- 10
+y <- 20
+g02 <- function() {
+  # x <- 1
+  # y <- 2
+  c(x, y)
+}
+g02()
+
+
+x <- 2
+g03 <- function() {
+  y <<- 1
+  c(x, y)
+}
+g03()
+
+y
+
+
+g07 <- function(x) { x + 1 }
+g08 <- function(fx) {
+  fx(10)
+}
+g08(log)
+
+
+h01 <- function(x) {
+  x
+  10
+}
+h01(stop("This is an error!"))
+
+
+
+show_time <- function(x = stop("Error!")) {
+  stop <- function(...) Sys.time()
+  print(stop("Error!"))
+}
+show_time()
+
+
+
+i01 <- function(y, z) {
+  list(y = y, z = z)
+}
+i02 <- function(x, ...) {
+  browser()
+  i01(...)
+}
+str(i02(x = 1, y = 2, z = 3))
+
+mysum <- function(...) {
+  invisible(sum(c(...)))
+}
+z <- mysum(1,2,3)
+z
+
+
+with_dir <- function(dir, code) {
+  old <- setwd(dir)
+  on.exit(setwd(old), add = TRUE)
+  stop()
+}
+getwd()
+
+
+3 + 1
+`+`(3, 1)
+
+`%myplus%` <- `+`
+`%+%`
+
+3 %myplus% 9
+
+
+dim() <- 1:2
+
+`dim<-`
+
+
+x <- list(1,2,3)
+names(x) <- c("a", "B", "c")
+
+`names<-`(x, c("a", "B", "c"))
+
+setNames(x, c("a", "B", "c"))
+x