Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.
from typing import Sequence
from .charts_scale_linear_scale import interpolate, pair ← linearScale, another function of this group · built into the same file, even by a slim install
from .math_ln import ln ← from math.ln ^1.0.0 · built alongside by fune
from .math_round_float import round_float ← from math.round-float ^1.0.0 · built alongside by fune
def log_scale(domain: Sequence[float], range: Sequence[float], value: float, clamp: bool) -> float:
"""Where value lands on a logarithmic axis: equal ratios take equal lengths.
The base cancels out, so there is none to pass. ln is math.ln, not
math.log, so every language lands on the same double.
"""
d0, d1 = pair(domain, "domain")
r0, r1 = pair(range, "range")
if not (d0 > 0) or not (d1 > 0):
raise ValueError(f"log scale domain must be positive; got [{d0}, {d1}]")
if d0 == d1:
raise ValueError(f"domain has no width: both ends are {d0}")
if not (value > 0):
raise ValueError(f"value must be positive for a log scale; got {value}")
l0 = ln(d0)
t = (ln(value) - l0) / (ln(d1) - l0)
if clamp:
t = max(0.0, min(1.0, t))
return round_float(interpolate(r0, r1, t), 6)