Update xlsw.py: fix timedelta support

[vinraspa]

fix timedelta support

With your PR, here is a check list:

• Has test cases written?
• Has all code lines tested?
• Has make format been run?
• Please update CHANGELOG.yml(not CHANGELOG.rst)
• Has fair amount of documentation if your change is complex
• Agree on NEW BSD License for your contribution

[codecov-commenter]

Codecov Report

Merging #49 (8f7e6f7) into dev (e309f9e) will increase coverage by 1.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev      #49      +/-   ##
==========================================
+ Coverage   97.42%   98.42%   +1.00%     
==========================================
  Files          13       13              
  Lines         698      697       -1     
==========================================
+ Hits          680      686       +6     
+ Misses         18       11       -7     

Impacted Files	Coverage Δ
pyexcel_xls/xlsr.py	99.24% <ø> (ø)
pyexcel_xls/xlsw.py	98.30% <100.00%> (+11.20%)	⬆️
tests/test_formatters.py	100.00% <100.00%> (ø)

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[chfw]

I am happy that you fix the problem. But does it make sense to support timedelta? So can you describe your use case?

[vinraspa]

I write a python program that must export ical events to a spreadsheet.
Events have a begin and end times (datetime) and duration (timedelta) fields.
I want user to be able to play with these fields (sum, min, max, ...)

Currently, with pyexcel module:

• xlsx format supports both datetime and timedelta (this is cool and this proves it's possible)
• xls format supports datime but not timedelta
• ods format supports timedelta but not datetime
  That is why I made PRs to pyexcel-xls, pyexcel-ods3 and pyexcel-io projects.

[chfw]

I see. But xlrd returns date time for timedelta. How do you translate it back to date time?

[vinraspa]

Yes, this is an issue
The conversion works only one way (python->xls) but not the other.
It would require xlrd deal differently when time format contains [H] or [HH] (instead of anything else).
I will think about it a bit.

Is it worth it? maybe you are right. After all, xls format is less and less used.

[chfw]

Xls has a limit on the number of rows so it is better to avoid using xls. UK’s national health service used xls format to persist collected reported COVID cases in 2020 and got a mystery problem: where did the data go? Oh well, xls skipped excessive rows.

[chfw]

I think we can release the change but note it in doc. Of course, If you are able to work out the remedying solution, and it can be added to the doc.

[vinraspa]

By 'the doc', do you mean 'README.rst'?