Conversion between calendar years (mostly BCE but also CE), astronomical dates, and the convention used for most ancient Greek dates, a span of two Julian years (for example, “431/430”).
The name comes from the ancient Greek formula for refering to years as ep' arkhontos ... (ἐπ᾽ ἄρχοντος ...) “when so-and-so was arkhon.”
pip install eparkhontos
eparkhontos can parse strings like “431/430”, “431/30”, “431/30
BCE”, “431-430 b.c.”, all of which will return an “astronomical
year”—an
integer which, for years BCE is negative and offset by 1 because 1 BCE
is numbered as 0. The astronomical year is assigned to the year in the
ancient Greek year begins, so "431/430" becomes -430 (meaning 431
BCE):
>>> import eparkhontos as epi
>>> epi.parse_arkhon("431/430")
-430
>>> epi.parse_arkhon("431/430 B.C.")
-430
>>> epi.parse_arkhon("431/430 BCE")
-430
>>> epi.parse_arkhon("431-30")
-430
If the string contains any form of “CE” or “AD” the year will be treated accordingly:
>>> epi.parse_arkhon("100/101 CE")
100
You can get a formatted arkhon year from an astronomical year, including BCE/CE appended if you want, or prepended if you want:
>>> epi.to_arkhon(-430)
'431/430'
>>> epi.to_arkhon(-430, with_era=True)
'431/430 BCE'
>>> epi.to_arkhon(-430, with_era=True, prefix_era=True)
'BCE 431/430'
>>> epi.to_arkhon(-430, True)
'431/430 BCE'
>>> epi.to_arkhon(-430, True, True)
'BCE 431/430'
>>> epi.to_arkhon(430, True)
'430/431 CE'
Note that “CE” is padded with leading space to align with “BCE.”
So you don’t have to remember how to correctly offset for an
astronomical year, you can convert an int or str. For instance, if
you want “431” to be interpreted as “431 BCE”:
>>> epi.to_astronomical(431)
-430
>>> epi.to_astronomical("431")
-430
If it is, in fact, a year CE:
>>> epi.to_astronomical("431", is_bce=False)
431
>>> epi.to_astronomical("431", False)
431
Bug reports and pull requests are welcome on GitHub at https://github.com/seanredmond/eparkhontos