A data frame is a matrix-like structure whose columns have the same length but may be of differing data types (e.g., numeric, logical, factor and character and so on).
1. > w <- data.frame(x = 1, y = 1:10, z=rep('A', 10));
2. > w <- data.frame(x = 1:2, y = 1:10, z=rep('A', 10));
3. > w <- data.frame(x = 1:3, y = 1:10, z=rep('A', 10));
4. > w <- data.frame(1:5, 1:10, rep('A', 10));