Add map2() walk through and examples

Author: cwickham

04-map2.R

@@ -0,0 +1,31 @@
+library(repurrrsive)
+gap_split_small <- gap_split[1:10]
+countries <- names(gap_split_small)
+
+# For each country create a ggplot of Life Expectancy through time 
+# with a title
+
+# For one country
+ggplot(gap_split_small[[1]], aes(year, lifeExp)) +
+  geom_line() +
+  labs(title = countries[[1]])
+
+# For all countries
+plots <- map2(gap_split_small, countries, 
+  ~ ggplot(.x, aes(year, lifeExp)) + 
+      geom_line() +
+      labs(title = .y))
+
+plots[[1]]
+# Display all plots
+walk(plots, print) # this might take awhile
+
+# Save all plots
+walk2(.x = plots, .y = countries, 
+  ~ ggsave(filename = paste0(.y, ".pdf"), plot = .x))
+
+# Argh! I didn't want all those pictures in this directory,
+# remove them all
+file.remove(paste0(countries, ".pdf"))
+
+