Add Grouped Stats Feature

This release addresses a recent ask for grouped statistics on a TSDF object. In particular, we know accept a frequency, group by the partition columns, and return the mean/sum/count/min/max/standard deviation for the grouping.

Upgrade Dependencies for Spark 3.2.1

• Modify code to work in Spark 3.2.1 and avoid APIs which may deprecate
• Update test code to use Delta Lake 1.1.0
• Update requirements

Performance update for Skewed AS OF Join

Update AS OF join logic to suppress warnings and avoid collect calls with a new flag (suppress_null_warnings) for AS OF join.

pypi 1.5 release - bug patch

Main change - Updated interpolation logic to use supplied timestamp column instead of hardcoding event_ts

pypi-release-0.1.4

Bump up PyPI Version, Update Visualizations in README

v0.1.2

• Resample has fill=True option for filling in zeros
• AS OF join now has option to retrieve NULL values from the 'right-hand' dataset (using skipNulls=False parameter)
• Update Resample Function to support custom windows (x minutes, y days) where x and y are integers
• Update the default to not prefix fields in the resample (bar calculations will continue to use preset high/open/low/close prefix)
• Bring Scala resample up to par with Python version
• Update README to refer to pypi project (dbl-tempo)
• Python logging now included to avoid print statements
• Bumping version

pypi-release

• added dbl-tempo to pypi (latest release v0.1.1
• updated README in python folder
• updated global README to show how to pip install with dbl-tempo package name

dbl-tempo-initial

Scope of enhancements

• remove required prefix from python resample logic (specify prefix for resampling) - bars calculation uses pre-set prefixing.
• update resample logic to accept interval-style strings (1 minute, 2 hours, etc) for more customization
• update scala version for changes above
• update error handling in python and scala for acceptable functions for aggregation in resample logic
• updated readme to account for changes above
• updated setup.py for pypi upload