reduce use of map_dfc and gather for code speedup in gg_miss_which

NEWS.md

@@ -2,8 +2,8 @@
 
 ## Minor Changes
 
-- Improved code in `miss_var_summary()`, `miss_var_table()`, and 
- `prop_miss_var()`, improving speed.
+- Improvements to code in `miss_var_summary()`, `miss_var_table()`, and 
+ `prop_miss_var()`, resulting in a 3-10x speedup.
 
 # naniar 0.5.1 (2020/04/10) "Uncle Andrew's Applewood Wardrobe"
 

R/gg-miss-which.R

@@ -23,10 +23,10 @@ gg_miss_which <- function(x){
 
   # tell us which columns have missing data
   ggobject <- x %>%
-    purrr::map_dfc(anyNA) %>%
-    purrr::map_dfc(function(x) ifelse(x == 0, "complete", "missing")) %>%
-    tidyr::gather(key = "variable",
-                  value = "value") %>%
+    miss_var_summary() %>%
+    dplyr::select(variable,
+                  value = n_miss) %>%
+    dplyr::mutate(value = dplyr::if_else(value == 0, "complete", "missing")) %>%
     dplyr::mutate(nheight = 1) %>%
     ggplot(data = .,
            aes(x = variable,