[Numpy-discussion] Add a total_seconds() method to timedelta64?

[Chris Barker]

I just noticed that there is no obvious way to convert a timedelta64 to
seconds (or some other easy unit) as a number.

The stdlib datetime.datetime has a .total_seconds() method for doing that.
I think it's a handy thing to have.

Looking at StackOverflow (and others), I see people suggesting things like:

a_timedelta.astype(np.float) / 1e6

This seems a really bad idea, as it's assuming the timedelta is storing
milliseconds.

The "proper" way to do it also suggested:

a_timedelta / np.timedelta64(1, 's')

This is, in fact, a much better way to do it, and allows you to specify
other units if you like: "ms"., "us", etc.

There was semi-recently a discussion thread on python-ideas about adding
other methods to datetime: (e.g.  .total_hours, .total_minutes). That was
pretty much rejected (or petered out anyway), and some argued that dividing
by a timedelta of the unit you want is the "right" way to do it anyway
(some argued that .total_seconds() never should have been added.

Personally I understand the "correctness" of using united-division, but
"practicality beats purity", and the discoverability of a method or two
really makes it easier on folks.

That being said, of folks don't want to add .total_seconds and the like --
we should add a bit to the docs about this, suggesting using the division
approach.

-CHB


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Christopher Barker, Ph.D.
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