time as float since Jan 1, 0001?

[Roy Smith]

I'm working with matplotlib.plot_date(), which represents time as
"floats starting at January 1st, year 0001". Is there any
straight-forward way to get that out of a datetime?

datetime.toordinal() gives me the number of days since that epoch, but
as an integer. I figured it wouldn't be too hard to just do:

t.toordinal() + t.time().total_seconds()

except it turns out that only timedelta supports total_seconds(); time
doesn't!

I suppose I could do:

t.toordinal() + t.hour / 24.0 \
+ t.minute / 1440.0 \
+ t.second / 86400.0

but that's really ugly. Is there no cleaner way to do this conversion?

 

[Mark Lawrence]

I'm working with matplotlib.plot_date(), which represents time as
"floats starting at January 1st, year 0001". Is there any
straight-forward way to get that out of a datetime?

datetime.toordinal() gives me the number of days since that epoch, but
as an integer. I figured it wouldn't be too hard to just do:

t.toordinal() + t.time().total_seconds()

except it turns out that only timedelta supports total_seconds(); time
doesn't!

I suppose I could do:

t.toordinal() + t.hour / 24.0 \
+ t.minute / 1440.0 \
+ t.second / 86400.0

but that's really ugly. Is there no cleaner way to do this conversion?

IIRC you needn't bother, matplotlib will do all the conversions for you.
In the highly likely case that I'm wrong this should help
http://matplotlib.org/api/dates_api.html#module-matplotlib.dates

 

[Chris Angelico]

datetime.toordinal() gives me the number of days since that epoch, but
as an integer. I figured it wouldn't be too hard to just do:

t.toordinal() + t.time().total_seconds()

What about t.timestamp()? That's since 1970, but you could add (if my
calculations are correct) 62135683200.0 to it.

ChrisA

 

[Roy Smith]

IIRC you needn't bother, matplotlib will do all the conversions for you.
In the highly likely case that I'm wrong this should help
http://matplotlib.org/api/dates_api.html#module-matplotlib.dates

Duh! I didn't get that far in the docs! Thanks, that makes life a lot
easier.

Still, it seems like allowing toordinal() and fromordinal() to handle
floats would be a useful addition

 

[Dennis Lee Bieber]

Still, it seems like allowing toordinal() and fromordinal() to handle
floats would be a useful addition

But "ordinals" aren't floats... <G>