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qiskit.utils.units의 소스 코드

# This code is part of Qiskit.
#
# (C) Copyright IBM 2017.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""SI unit utilities"""

from typing import Tuple, Optional, Union

import numpy as np

from qiskit.circuit.parameterexpression import ParameterExpression


[문서]def apply_prefix(value: Union[float, ParameterExpression], unit: str) -> float: """ Given a SI unit prefix and value, apply the prefix to convert to standard SI unit. Args: value: The number to apply prefix to. unit: String prefix. Returns: Converted value. .. note:: This may induce tiny value error due to internal representation of float object. See https://docs.python.org/3/tutorial/floatingpoint.html for details. Raises: ValueError: If the ``units`` aren't recognized. """ prefactors = { "f": -15, "p": -12, "n": -9, "u": -6, "µ": -6, "m": -3, "k": 3, "M": 6, "G": 9, "T": 12, "P": 15, } if not unit or len(unit) == 1: # for example, "m" can represent meter return value if unit[0] not in prefactors: raise ValueError(f"Could not understand unit: {unit}") pow10 = prefactors[unit[0]] # to avoid round-off error of prefactor if pow10 < 0: return value / pow(10, -pow10) return value * pow(10, pow10)
[문서]def detach_prefix(value: float, decimal: Optional[int] = None) -> Tuple[float, str]: """ Given a SI unit value, find the most suitable prefix to scale the value. For example, the ``value = 1.3e8`` will be converted into a tuple of ``(130.0, "M")``, which represents a scaled value and auxiliary unit that may be used to display the value. In above example, that value might be displayed as ``130 MHz`` (unit is arbitrary here). Example: >>> value, prefix = detach_prefix(1e4) >>> print(f"{value} {prefix}Hz") 10 kHz Args: value: The number to find prefix. decimal: Optional. An arbitrary integer number to represent a precision of the value. If specified, it tries to round the mantissa and adjust the prefix to rounded value. For example, 999_999.91 will become 999.9999 k with ``decimal=4``, while 1.0 M with ``decimal=3`` or less. Returns: A tuple of scaled value and prefix. .. note:: This may induce tiny value error due to internal representation of float object. See https://docs.python.org/3/tutorial/floatingpoint.html for details. Raises: ValueError: If the ``value`` is out of range. ValueError: If the ``value`` is not real number. """ prefactors = { -15: "f", -12: "p", -9: "n", -6: "µ", -3: "m", 0: "", 3: "k", 6: "M", 9: "G", 12: "T", 15: "P", } if not np.isreal(value): raise ValueError(f"Input should be real number. Cannot convert {value}.") if np.abs(value) != 0: pow10 = int(np.floor(np.log10(np.abs(value)) / 3) * 3) else: pow10 = 0 # to avoid round-off error of prefactor if pow10 > 0: mant = value / pow(10, pow10) else: mant = value * pow(10, -pow10) if decimal is not None: # Corner case handling # For example, 999_999.99 can be rounded to 1000.0 k rather than 1.0 M. mant = np.round(mant, decimal) if mant >= 1000: mant /= 1000 pow10 += 3 if pow10 not in prefactors: raise ValueError(f"Value is out of range: {value}") return mant, prefactors[pow10]