Emergent mode fails with `AttributeError: 'str' object has no attribute 'isocalendar'`

[pjlegato]

Describe the bug
When running with -emt, CSV input, and a date field given in the required format YYYY/MM/DD, it crashes with:

  File "/Users/paul/src/pyGrams/scripts/tfidf_reduce.py", line 77, in <listcomp>
    [d.isocalendar() for d in dates]]
AttributeError: 'str' object has no attribute 'isocalendar'

The code does not appear to be parsing the input date string as a date object; it attempts to call date methods on a string.

To Reproduce
Steps to reproduce the behavior:

1. Create a CSV input file with a date field in YYYY/MM/DD format
2. Run python pygrams.py -emt -ds=posts.csv -dh='date' -th text > emergent.out
3. Crashes with above error

Expected behavior
Should not crash; should calculate emerging terms.

Desktop (please complete the following information):

• OS: Mac OS
• Python 3.7.2

[thanasions]

Thanks for raising the issue. We are currently looking into this!

[IanGrimstead]

Created branch 227-bug-csv-date

[IanGrimstead]

3.7.3 running under Xenial linux dist; appveyor should be ok (worked with 3.7) - awaiting build...
So we should be fine with >3.7