Collapse repeated columns into rows [duplicate]

Answer 1

This can be done with melt from data.table which can take multiple columns in the measure by specifying the pattern

library(data.table)#v1.9.6+
melt(setDT(df1), measure=patterns('Title', 'Year', 'Rating'), 
    value.name=c('Title', 'Year', 'Rating'))[,variable:=NULL][]
#     Title Year Rating
#1: Movie 1 1997    6.7
#2: Movie 2 1987    8.2
#3: Movie 3 2009    7.1

data

df1 <- structure(list(Title = "Movie 1", Year = 1997L, Rating = 6.7, 
Title = "Movie 2", Year = 1987L, Rating = 8.2, Title = "Movie 3", 
Year = 2009L, Rating = 7.1), .Names = c("Title", "Year", 
"Rating", "Title", "Year", "Rating", "Title", "Year", "Rating"
), class = "data.frame", row.names = c(NA, -1L))