Add/rename/link pmap example

README.md

@@ -21,6 +21,7 @@ Not all are used in webinar
   * **Working with non-vectorized functions.** [`ex04_map-example`](ex04_map-example.md) Small example using `purrr::map()` to apply `nrow()` to list of data frames.
   * **Row-wise thinking vs. column-wise thinking.** [`ex05_attack-via-rows-or-columns`](ex05_attack-via-rows-or-columns.md) Data rectangling example. Both are possible, but I find building a tibble column-by-column is less aggravating than building rows, then row binding.
   * **Iterate over rows of a data frame.** [`iterate-over-rows`](iterate-over-rows.md) Empirical study of reshaping a data frame into this form: a list with one component per row. Revisiting a study originally done by Winston Chang. Run times for different number of [rows](row-benchmark.png) or [columns](col-benchmark.png).
+  * **Generate data from different distributions via `purrr::pmap()`.** [`ex06_runif-via-pmap`](ex06_runif-via-pmap.md) Use `purrr::pmap()` to generate U[min, max] data for various combinations of (n, min, max), stored as rows of a data frame.
   * **Split-apply-combine.** Nesting vs splitting.
     - Downside of `split()`: First-class grouping variable(s) --> character vector of names --> variable is a big drag. Integer-y numerics must be coerced back, factors must be recreated, with original levels. Transitting data through attributes is an anti-pattern.
     - Downside of `nest()`: When you inspect the list-column, you can't see values of grouping (key) variables. Grouping variables not necessarily/easily available for simple map (coolbutuseless's posts and PR).

ex07_runif-row-wise.R → ex06_runif-via-pmap.R

@@ -137,6 +137,12 @@ my_runif <- function(n, min, max, ...) runif(n, min, max)
 set.seed(123)
 pmap(df_oops, my_runif)
 
+#' ## Add the generated data to the data frame as a list-column
+set.seed(123)
+(df_aug <- df %>%
+    mutate(data = pmap(., runif)))
+#View(df_aug)
+
 #' ## Review
 #'
 #' What have we done?
@@ -148,3 +154,4 @@ pmap(df_oops, my_runif)
 #'   * Wrote custom wrappers around `runif()` to deal with:
 #'     - df var names != `.f()` arg names
 #'     - df vars that aren't formal args of `.f()`
+#'   * Added generated data as a list-column

ex07_runif-row-wise.md → ex06_runif-via-pmap.md

@@ -252,6 +252,21 @@ pmap(df_oops, my_runif)
 #> [1] 894.7157 946.4206 141.0008
 ```
 
+## Add the generated data to the data frame as a list-column
+
+``` r
+set.seed(123)
+(df_aug <- df %>%
+    mutate(data = pmap(., runif)))
+#> # A tibble: 3 x 4
+#>       n   min   max data     
+#>   <int> <dbl> <dbl> <list>   
+#> 1     1    0.    1. <dbl [1]>
+#> 2     2   10.  100. <dbl [2]>
+#> 3     3  100. 1000. <dbl [3]>
+#View(df_aug)
+```
+
 ## Review
 
 What have we done?
@@ -263,3 +278,4 @@ What have we done?
   - Wrote custom wrappers around `runif()` to deal with:
       - df var names \!= `.f()` arg names
       - df vars that aren’t formal args of `.f()`
+  - Added generated data as a list-column