By the way, `df[20:50,:]` is *not* a subset of `df`, but a *copy* of a subset of `df`. Since `df` doesn't have any column whose name is "row", how could you expect the "row" to be an index.
On Monday, August 24, 2015 at 6:28:30 PM UTC+2, Robert Smith wrote: > > In my opinion, when you did `df[20:50,:]`, you constructed a new >> DataFrame, which had no longer anything to do with the original `df`. So >> you cannot expect it to know the original position in `df`. And when you >> print it, the row number (instead of index) is generated on the fly, just >> let you know which value is at which line of the output. >> >> I think what needed here is just a formatted `print()` for DataFrame, >> which can toggle the row number index. >> > > When I do `df[20:50,:]`, the result is a subset of the original DataFrame > `df`, so I should expect to keep track of the index in `df`. It doesn't > take much to see why that is useful (an index often refers to a person, > geographical entity, discrete period of time, etc). >
