Fix complex coercion

Author: rdpeng

02_RProgramming/DataTypes/index.Rmd

@@ -200,7 +200,9 @@ NAs introduced by coercion
 > as.logical(x)
 [1] NA NA NA
 > as.complex(x)
-[1] 0+0i 1+0i 2+0i 3+0i 4+0i 5+0i 6+0i
+[1] NA NA NA
+Warning message:
+NAs introduced by coercion 
 ```
 
 ---
@@ -472,4 +474,4 @@ Data Types
 
 - data frames
 
-- names
+- names