imporve vignette

vignettes/start.Rmd

@@ -44,12 +44,15 @@ fd_filter(DFD, "B", 3)
 ### Find index of element in column-list matching with a key using `fd_match`
 
 ```{r match}
+# add new column
 DFD = fd_add(DFD, "C", function(i) sample(1:5, 5))
+DFD
 
+# apply 'fd_match'
 idMatch = fd_match(DFD, "C", 4)
 idMatch
 
-# to check this:
+# check with 'fd_filter'
 fd_filter(DFD, "C", idMatch)
 ```
 
@@ -62,7 +65,10 @@ fd_melt(DFD, "B", keep = list("A", "C"))
 when two column-lists have the same length for each elements, we can melt in the same time
 
 ```{r meltDouble}
+# add new column with element of same length between 'B' and 'B2'
 DFD = fd_add(DFD, "B2", function(i) 1:length(DFD$B[[i]]))
+DFD
 
+# apply 'fd_melt'
 fd_melt(DFD, "B", "B2", keep = list("A", "C"))
 ```