pd.merge fails on datetime columns with tzinfo #11405
Description
Since pandas-0.17 a merge on a datetime column fails if the datetime is tz-aware, see example below. Possibly related to #9663?
import pandas as pd from datetime import datetime from dateutil.tz import gettz import sys, os import traceback as tbm # works a = pd.DataFrame({'created' : [datetime(2015,10,10), datetime(2015,10,20)], 'count' : [1,2]}) b = pd.DataFrame({'created' : [datetime(2015,10,10), datetime(2015,10,20)], 'count' : [1,2]}) pd.merge(a, b, how='outer') # doesn't work (used to work on pandas-0.16.2) try: utc = gettz('UTC') a = pd.DataFrame({'created' : [datetime(2015,10,10, tzinfo=utc), datetime(2015,10,20, tzinfo=utc)], 'count' : [1,2]}) b = pd.DataFrame({'created' : [datetime(2015,10,10, tzinfo=utc), datetime(2015,10,20, tzinfo=utc)], 'count' : [1,2]}) pd.merge(a, b, how='outer') except Exception as e: print "Yeah, doesn't work: %s" % e _, _, tb = sys.exc_info() stack = lambda n : tbm.extract_tb(tb, 99)[n][0:] print "called from", stack(0) print "failing statement", stack(-1) =>
Yeah, doesn't work: type object argument after * must be a sequence, not itertools.imap called from ('<ipython-input-194-3c3669b26a55>', 23, '<module>', u"pd.merge(a, b, how='outer')") failing statement ('/.../local/lib/python2.7/site-packages/pandas/tools/merge.py', 516, '_get_join_indexers', 'llab, rlab, shape = map(list, zip( * map(fkeys, left_keys, right_keys)))') the culprit seems to be in the call to _factorize_keys though I couldn't quite figure out what goes wrong.
Version info
$ python --version Python 2.7.6 $ pip freeze | grep pandas pandas==0.17.0