I was reading the documentation for Julia's Dataframe package, and the package implements Dataframe by a series of a columns each of a single type. From reading the docs, it looks like that's how R implements Dataframes as well. Is there any reason this is a better way than having a Dataframe being a collection of tuples with elements of different types? The later seems more natural to me.What are the trade-offs or reasons one would implement Dataframes as a list of columns vs a list of rows? 
What are the tradeoffs between implenting dataframes as a series of columns vs a series of tuples
data structures;statistics