Minimise base-R a little

base-R.qmd

@@ -192,7 +192,10 @@ Base R also provides a function that combines the features of `filter()` and `se
 df |> 
   filter(x > 1) |> 
   select(y, z)
+```
 
+```{r}
+#| results: false
 # same as
 df |> subset(x > 1, c(y, z))
 ```
@@ -304,7 +307,9 @@ l <- list(
 
     ```{r}
     str(l[1:2])
+
     str(l[1])
+
     str(l[4])
     ```
 
@@ -315,67 +320,38 @@ l <- list(
 
     ```{r}
     str(l[[1]])
+
     str(l[[4]])
 
     str(l$a)
     ```
 
 The difference between `[` and `[[` is particularly important for lists because `[[` drills down into the list while `[` returns a new, smaller list.
-To help you remember the difference, take a look at the an unusual pepper shaker shown in @fig-pepper-1.
-If this pepper shaker is your list `pepper`, then, `pepper[1]` is a pepper shaker containing a single pepper packet, as in @fig-pepper-2.
-If we suppose this pepper shaker is a list `pepper`, then, `pepper[1]` is a pepper shaker containing a single pepper packet, as in @fig-pepper-2.
+To help you remember the difference, take a look at the an unusual pepper shaker shown in @fig-pepper.
+If this pepper shaker is your list `pepper`, then, `pepper[1]` is a pepper shaker containing a single pepper packet.
+If we suppose this pepper shaker is a list `pepper`, then, `pepper[1]` is a pepper shaker containing a single pepper packet.
 `pepper[2]` would look the same, but would contain the second packet.
 `pepper[1:2]` would be a pepper shaker containing two pepper packets.
-`pepper[[1]]` would extract the pepper packet itself, as in @fig-pepper-3.
+`pepper[[1]]` would extract the pepper packet itself.
 
 ```{r}
-#| label: fig-pepper-1
+#| label: fig-pepper
 #| echo: false
-#| out-width: "25%"
+#| out-width: "100%"
 #| fig-cap: >
-#|   A pepper shaker that Hadley once found in his hotel room.
+#|   (Left) A pepper shaker that Hadley once found in his hotel room.
+#|   (Middle) `pepper[1]`.
+#|   (Right) `pepper[[1]]`
 #| fig-alt: >
-#|   A photo of a glass pepper shaker. Instead of the pepper shaker
-#|   containing pepper, it contains many packets of pepper.
+#|   Three photos. On the left is a photo of a glass pepper shaker. Instead of 
+#|   the pepper shaker containing pepper, it contain a single packet of pepper.
+#|   In the middle is a photo of a single packet of pepper. On the right is a 
+#|   photo the contents of packet of pepper.
 
-knitr::include_graphics("images/pepper.jpg")
+knitr::include_graphics("diagrams/pepper.png")
 ```
 
-```{r}
-#| label: fig-pepper-2
-#| echo: false
-#| out-width: "25%"
-#| fig-cap: >
-#|   `pepper[1]`
-#| fig-alt: >
-#|   A photo of the glass pepper shaker containing just one packet of 
-#|   pepper.
-
-knitr::include_graphics("images/pepper-1.jpg")
-```
-
-```{r}
-#| label: fig-pepper-3
-#| echo: false
-#| out-width: "25%"
-#| fig-cap: >
-#|   `pepper[[1]]`
-#| fig-alt: A photo of single packet of pepper.
-
-knitr::include_graphics("images/pepper-2.jpg")
-```
-
-This same principle applies when you use 1d `[` with a data frame:
-
-```{r}
-df <- tibble(x = 1:3, y = 3:5)
-
-# returns a one-column data frame
-df["x"]
-
-# returns the contents of x
-df[["x"]]
-```
+This same principle applies when you use 1d `[` with a data frame: `df["x"]` returns a one-column data frame and `df[["x"]]` returns a vector.
 
 ### Exercises