35 lines
1.3 KiB
Python
35 lines
1.3 KiB
Python
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"""Halving calendar and position within the halving cycle."""
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import numpy as np
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import pandas as pd
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GENESIS = pd.Timestamp("2009-01-03")
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# Block heights 210k, 420k, 630k, 840k (UTC dates).
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HALVINGS = pd.DatetimeIndex(["2012-11-28", "2016-07-09", "2020-05-11", "2024-04-20"])
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# Later halvings are projected at the length of the last cycle. Block times drift
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# by weeks per cycle, which is noise at the resolution this is used.
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_LAST_CYCLE = HALVINGS[-1] - HALVINGS[-2]
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_PROJECTED = pd.DatetimeIndex([HALVINGS[-1] + k * _LAST_CYCLE for k in range(1, 6)])
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# Genesis starts cycle 0.
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CYCLE_STARTS = pd.DatetimeIndex([GENESIS]).append(HALVINGS).append(_PROJECTED)
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def cycle_position(dates) -> tuple[np.ndarray, np.ndarray]:
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"""
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For each date, return (cycle index, days since that cycle began).
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Cycle 0 runs from genesis to the first halving; a halving day is day 0 of
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the cycle it starts.
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"""
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dates = pd.DatetimeIndex(dates)
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if (dates < GENESIS).any():
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raise ValueError("date before genesis")
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if (dates >= CYCLE_STARTS[-1]).any():
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raise ValueError("date beyond projected halvings")
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index = CYCLE_STARTS.searchsorted(dates, side="right") - 1
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days = (dates - CYCLE_STARTS[index]).days
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return np.asarray(index), np.asarray(days)
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