ENH: TimeDeltaIndex and corresponding scalar

[jreback]

• disallow operations in series that are invalid that now create timedelta64
  (e.g. dt + dt, only dt - dt?) BUG/API: Fix operating with timedelta64/pd.offsets on rhs of a datelike series/index #4534
• create the TimeDeltaIndex object, inherit from Int64, ENH: create Timedelta scalar / TimedeltaIndex #8184
• create associated scalar (np.timedelta64 wrapper), like
  Timestamp (Timedelta?), direct wrapper might work, ENH: create Timedelta scalar / TimedeltaIndex #8184
  that forwards methods, internally repr as timedelta64 (or view?) as array
• move pretty printing to the new class (from function in lib), done???
  see Weird Datetime Behaviour #3002 and ENH: support min/max on timedelta64[ns] Series #2990, ENH: timedelta should write correctly to csv #4378
• need a Timedelta64 Block, with to_native_types (for printing), PR ENH: GH3371 support timedelta fillna #4684
• read_csv to have a parse_timedelta to automatically apply the dtype, see API: add parse_timedelta kw for read_csv #4650, ENH: GH3371 support timedelta fillna #4684, moved to ENH: read_csv to have a parse_timedelta kw to automatically parse into timedelta64  #8185

[cpcloud]

This would be totally awesome, especially for any kind of experimental data.

[jreback]

there is already quite a lot of support, see the time delta section (in time series part of docs)
this is just an extension to make it easier to do some things
eg the index is works but its am Int64Index, so a bit non-intuitive

[cpcloud]

ha! didn't realize i had seen this already

[hughesadam87]

For reference (as #7640) was not the appropriate place to share, here's a hacked implementation of datetime --> timeinterval.

http://nbviewer.ipython.org/github/hugadams/pyuvvis/blob/master/examples/Notebooks/intervals.ipynb

I'd imagine the TimeDeltaIndex should supplant the need for such an API entirely.