--- a/r.rst	Sun Mar 06 00:25:36 2016 +0200
+++ b/r.rst	Sun Mar 06 00:27:25 2016 +0200
@@ -223,3 +223,7 @@
   dfnew <- df[-ncol(df)]  # last
   dfnew <- df[-c(1, 3:4, 7)]  # range
 
+Drop column from data frame by name::
+
+  newdf <- df[ , !(names(df) %in% c("lat", "long"))]
+