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#!/usr/bin/env python3
"""
pint-convert
~~~~~~~~~~~~
:copyright: 2020 by Pint Authors, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
"""
from __future__ import annotations
import argparse
import re
from pint import UnitRegistry
parser = argparse.ArgumentParser(description="Unit converter.", usage=argparse.SUPPRESS)
parser.add_argument(
"-s",
"--system",
metavar="sys",
default="SI",
help="unit system to convert to (default: SI)",
)
parser.add_argument(
"-p",
"--prec",
metavar="n",
type=int,
default=12,
help="number of maximum significant figures (default: 12)",
)
parser.add_argument(
"-u",
"--prec-unc",
metavar="n",
type=int,
default=2,
help="number of maximum uncertainty digits (default: 2)",
)
parser.add_argument(
"-U",
"--no-unc",
dest="unc",
action="store_false",
help="ignore uncertainties in constants",
)
parser.add_argument(
"-C",
"--no-corr",
dest="corr",
action="store_false",
help="ignore correlations between constants",
)
parser.add_argument(
"fr", metavar="from", type=str, help="unit or quantity to convert from"
)
parser.add_argument("to", type=str, nargs="?", help="unit to convert to")
try:
args = parser.parse_args()
except SystemExit:
parser.print_help()
raise
ureg = UnitRegistry()
ureg.auto_reduce_dimensions = True
ureg.autoconvert_offset_to_baseunit = True
ureg.enable_contexts("Gau", "ESU", "sp", "energy", "boltzmann")
ureg.default_system = args.system
def _set(key: str, value):
obj = ureg._units[key].converter
object.__setattr__(obj, "scale", value)
if args.unc:
import uncertainties
# Measured constants subject to correlation
# R_i: Rydberg constant
# g_e: Electron g factor
# m_u: Atomic mass constant
# m_e: Electron mass
# m_p: Proton mass
# m_n: Neutron mass
R_i = (ureg._units["R_inf"].converter.scale, 0.0000000000021e7)
g_e = (ureg._units["g_e"].converter.scale, 0.00000000000035)
m_u = (ureg._units["m_u"].converter.scale, 0.00000000050e-27)
m_e = (ureg._units["m_e"].converter.scale, 0.00000000028e-30)
m_p = (ureg._units["m_p"].converter.scale, 0.00000000051e-27)
m_n = (ureg._units["m_n"].converter.scale, 0.00000000095e-27)
if args.corr:
# Correlation matrix between measured constants (to be completed below)
# R_i g_e m_u m_e m_p m_n
corr = [
[1.0, -0.00206, 0.00369, 0.00436, 0.00194, 0.00233], # R_i
[-0.00206, 1.0, 0.99029, 0.99490, 0.97560, 0.52445], # g_e
[0.00369, 0.99029, 1.0, 0.99536, 0.98516, 0.52959], # m_u
[0.00436, 0.99490, 0.99536, 1.0, 0.98058, 0.52714], # m_e
[0.00194, 0.97560, 0.98516, 0.98058, 1.0, 0.51521], # m_p
[0.00233, 0.52445, 0.52959, 0.52714, 0.51521, 1.0],
] # m_n
(R_i, g_e, m_u, m_e, m_p, m_n) = uncertainties.correlated_values_norm(
[R_i, g_e, m_u, m_e, m_p, m_n], corr
)
else:
R_i = uncertainties.ufloat(*R_i)
g_e = uncertainties.ufloat(*g_e)
m_u = uncertainties.ufloat(*m_u)
m_e = uncertainties.ufloat(*m_e)
m_p = uncertainties.ufloat(*m_p)
m_n = uncertainties.ufloat(*m_n)
_set("R_inf", R_i)
_set("g_e", g_e)
_set("m_u", m_u)
_set("m_e", m_e)
_set("m_p", m_p)
_set("m_n", m_n)
# Measured constants with zero correlation
_set(
"gravitational_constant",
uncertainties.ufloat(
ureg._units["gravitational_constant"].converter.scale, 0.00015e-11
),
)
_set(
"d_220",
uncertainties.ufloat(ureg._units["d_220"].converter.scale, 0.000000032e-10),
)
_set(
"K_alpha_Cu_d_220",
uncertainties.ufloat(
ureg._units["K_alpha_Cu_d_220"].converter.scale, 0.00000022
),
)
_set(
"K_alpha_Mo_d_220",
uncertainties.ufloat(
ureg._units["K_alpha_Mo_d_220"].converter.scale, 0.00000019
),
)
_set(
"K_alpha_W_d_220",
uncertainties.ufloat(
ureg._units["K_alpha_W_d_220"].converter.scale, 0.000000098
),
)
ureg._root_units_cache = dict()
ureg._build_cache()
def convert(u_from, u_to=None, unc=None, factor=None):
q = ureg.Quantity(u_from)
fmt = f".{args.prec}g"
if unc:
q = q.plus_minus(unc)
if u_to:
nq = q.to(u_to)
else:
nq = q.to_base_units()
if factor:
q *= ureg.Quantity(factor)
nq *= ureg.Quantity(factor).to_base_units()
prec_unc = use_unc(nq.magnitude, fmt, args.prec_unc)
if prec_unc > 0:
fmt = f".{prec_unc}uS"
else:
try:
nq = nq.magnitude.n * nq.units
except Exception:
pass
fmt = "{:" + fmt + "} {:~P}"
print(("{:} = " + fmt).format(q, nq.magnitude, nq.units))
def use_unc(num, fmt, prec_unc):
unc = 0
try:
if isinstance(num, uncertainties.UFloat):
full = ("{:" + fmt + "}").format(num)
unc = re.search(r"\+/-[0.]*([\d.]*)", full).group(1)
unc = len(unc.replace(".", ""))
except Exception:
pass
return max(0, min(prec_unc, unc))
def main():
convert(args.fr, args.to)
if __name__ == "__main__":
main()
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