Extract ex04

inside-the-box.R → ex04_attack-via-rows-or-columns.R

@@ -1,5 +1,5 @@
 #' ---
-#' title: "Thinking Inside the Box"
+#' title: "Attack via rows or columns?"
 #' author: "Jenny Bryan"
 #' date: "`r format(Sys.Date())`"
 #' output: github_document
@@ -13,21 +13,18 @@ knitr::opts_chunk$set(
 )
 options(tidyverse.quiet = TRUE)
 
+#' **WARNING: half-baked**
+
 #+ body
 # ----
 library(tidyverse)
 
-
 # ----
 #' ## If you must sweat, compare row-wise work vs. column-wise work
 #'
 #' The approach you use in that first example is not always the one that scales
 #' up the best.
 
-sapply(df, class)
-class(df[1, ])
-class(iris[14, ])
-
 x <- list(
   list(name = "sue", number = 1, veg = c("onion", "carrot")),
   list(name = "doug", number = 2, veg = c("potato", "beet"))
@@ -51,22 +48,3 @@ tibble(
   number = map_dbl(x, "number"),
   veg = map(x, "veg")
 )
-
-# add_row()
-# rbind(df, as.data.frame(t(v2)))
-# https://stackoverflow.com/questions/22581122/how-to-add-a-named-vector-as-a-row-to-a-data-frame
-
-## iterating over rows
-## specific problem from dean: transforming a dataframe into a list of rows
-## (the format that Javascript d3 expects)
-# split(x, seq_len(nrow(x))) then lapply (or purrr::map)
-# lapply(seq_len(nrow(df)), function(i) as.list(df[i,,drop=F]))
-# for (i in seq_len(nrow(df)) {...}
-# for(i in seq_along(df[,1]){df[i,]}
-# lapply(seq(nrow(df)), function(i) { row <- df[i,] }
-# ## jim hester
-# lapply(seq_len(NROW(df)), function(i) val = df[i, , drop = FALSE])
-
-pmap(head(iris), list)
-
-View(mtcars)

ex04_attack-via-rows-or-columns.md

@@ -0,0 +1,69 @@
+Attack via rows or columns?
+================
+Jenny Bryan
+2018-04-02
+
+**WARNING: half-baked**
+
+``` r
+library(tidyverse)
+```
+
+## If you must sweat, compare row-wise work vs. column-wise work
+
+The approach you use in that first example is not always the one that
+scales up the best.
+
+``` r
+x <- list(
+  list(name = "sue", number = 1, veg = c("onion", "carrot")),
+  list(name = "doug", number = 2, veg = c("potato", "beet"))
+)
+
+# row binding
+
+# frustrating base attempts
+rbind(x)
+#>   [,1]   [,2]  
+#> x List,3 List,3
+do.call(rbind, x)
+#>      name   number veg        
+#> [1,] "sue"  1      Character,2
+#> [2,] "doug" 2      Character,2
+do.call(rbind, x) %>% str()
+#> List of 6
+#>  $ : chr "sue"
+#>  $ : chr "doug"
+#>  $ : num 1
+#>  $ : num 2
+#>  $ : chr [1:2] "onion" "carrot"
+#>  $ : chr [1:2] "potato" "beet"
+#>  - attr(*, "dim")= int [1:2] 2 3
+#>  - attr(*, "dimnames")=List of 2
+#>   ..$ : NULL
+#>   ..$ : chr [1:3] "name" "number" "veg"
+
+# tidyverse fail
+bind_rows(x)
+#> Error in bind_rows_(x, .id): Argument 3 must be length 1, not 2
+map_dfr(x, ~ .x)
+#> Error in bind_rows_(x, .id): Argument 3 must be length 1, not 2
+
+map_dfr(x, ~ .x[c("name", "number")])
+#> # A tibble: 2 x 2
+#>   name  number
+#>   <chr>  <dbl>
+#> 1 sue       1.
+#> 2 doug      2.
+
+tibble(
+  name = map_chr(x, "name"),
+  number = map_dbl(x, "number"),
+  veg = map(x, "veg")
+)
+#> # A tibble: 2 x 3
+#>   name  number veg      
+#>   <chr>  <dbl> <list>   
+#> 1 sue       1. <chr [2]>
+#> 2 doug      2. <chr [2]>
+```