"""
Exception classes defined by unyt
"""
# -----------------------------------------------------------------------------
# Copyright (c) 2018, yt Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the LICENSE file, distributed with this software.
# -----------------------------------------------------------------------------
[docs]class UnitOperationError(ValueError):
"""An exception that is raised when unit operations are not allowed
Example
-------
>>> import unyt as u
>>> 3*u.g + 4*u.m\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.UnitOperationError: The <ufunc 'add'> operator
for unyt_arrays with units "g" (dimensions "(mass)") and
"m" (dimensions "(length)") is not well defined.
"""
def __init__(self, operation, unit1, unit2=None):
self.operation = operation
self.unit1 = unit1
self.unit2 = unit2
ValueError.__init__(self)
def __str__(self):
err = (
'The %s operator for unyt_arrays with units "%s" '
'(dimensions "%s") ' % (self.operation, self.unit1, self.unit1.dimensions)
)
if self.unit2 is not None:
err += 'and "%s" (dimensions "%s") ' % (self.unit2, self.unit2.dimensions)
err += "is not well defined."
return err
[docs]class UnitConversionError(Exception):
"""An error raised when converting to a unit with different dimensions.
Example
-------
>>> import unyt as u
>>> data = 3*u.g
>>> data.to('m') # doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.UnitConversionError: Cannot convert between 'g'
(dim '(mass)') and 'm' (dim '(length)').
"""
def __init__(self, unit1, dimension1, unit2, dimension2):
self.unit1 = unit1
self.unit2 = unit2
self.dimension1 = dimension1
self.dimension2 = dimension2
Exception.__init__(self)
def __str__(self):
err = "Cannot convert between '%s' (dim '%s') and '%s' " "(dim '%s')." % (
self.unit1,
self.dimension1,
self.unit2,
self.dimension2,
)
return err
[docs]class MissingMKSCurrent(Exception):
"""Raised when querying a unit system for MKS current dimensions
Since current is a base dimension for SI or SI-like unit systems but not in
CGS or CGS-like unit systems, dimensions that include the MKS current
dimension (the dimension of ampere) are not representable in CGS-like unit
systems. When a CGS-like unit system is queried for such a dimension, this
error is raised.
Example
-------
>>> from unyt.unit_systems import cgs_unit_system as us
>>> from unyt import ampere
>>> us[ampere.dimensions]\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.MissingMKSCurrent: The cgs unit system does not
have a MKS current base unit
"""
def __init__(self, unit_system_name):
self.unit_system_name = unit_system_name
def __str__(self):
err = (
"The %s unit system does not have a MKS current base unit"
% self.unit_system_name
)
return err
[docs]class MKSCGSConversionError(Exception):
"""Raised when conversion between MKS and CGS units cannot be performed
This error is raised and caught internally and will expose itself
to the user as part of a chained exception leading to a
UnitConversionError.
"""
pass
[docs]class UnitsNotReducible(Exception):
"""Raised when a unit cannot be safely represented in a unit system
Example
-------
>>> from unyt import A, cm
>>> data = 12*A/cm
>>> data.in_cgs()\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.UnitsNotReducible: The unit "A/cm" (dimensions
"(current_mks)/(length)") cannot be reduced to an expression
within the cgs system of units.
"""
def __init__(self, unit, units_base):
self.unit = unit
self.units_base = units_base
Exception.__init__(self)
def __str__(self):
err = (
'The unit "%s" (dimensions "%s") cannot be reduced to an '
"expression within the %s system of units."
% (self.unit, self.unit.dimensions, self.units_base)
)
return err
[docs]class IterableUnitCoercionError(Exception):
"""Raised when an iterable cannot be converted to a unyt_array
Example
-------
>>> from unyt import g, cm, unyt_array
>>> data = [2*cm, 3*g]
>>> unyt_array(data)\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.IterableUnitCoercionError: Received an input
or operand that cannot be converted to a unyt_array with uniform
units:
[unyt_quantity(2., 'cm'), unyt_quantity(3., 'g')]
"""
def __init__(self, op):
self.op = op
def __str__(self):
err = (
"Received an input or operand that cannot be converted "
f"to a unyt_array with uniform units: {self.op}"
)
return err
[docs]class InvalidUnitEquivalence(Exception):
"""Raised an equivalence does not apply to a unit conversion
Example
-------
>>> import unyt as u
>>> data = 12*u.g
>>> data.to('erg', equivalence='thermal')\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.InvalidUnitEquivalence: The unit equivalence
'thermal' does not exist for the units 'g' and 'erg'.
"""
def __init__(self, equiv, unit1, unit2):
self.equiv = equiv
self.unit1 = unit1
self.unit2 = unit2
def __str__(self):
from unyt.unit_object import Unit
if isinstance(self.unit2, Unit):
msg = (
"The unit equivalence '%s' does not exist for the units "
"'%s' and '%s'."
)
else:
msg = (
"The unit equivalence '%s' does not exist for units '%s' "
"to convert to a new unit with dimensions '%s'."
)
return msg % (self.equiv, self.unit1, self.unit2)
[docs]class InvalidUnitOperation(Exception):
"""Raised when an operation on a unit object is not allowed
Example
-------
>>> from unyt import cm, g
>>> cm + g # doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.InvalidUnitOperation: addition with unit objects
is not allowed
"""
pass
[docs]class SymbolNotFoundError(Exception):
"""Raised when a unit name is not available in a unit registry
Example
-------
>>> from unyt.unit_registry import default_unit_registry
>>> default_unit_registry['made_up_unit']\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.SymbolNotFoundError: The symbol 'made_up_unit'
does not exist in this registry.
"""
pass
[docs]class UnitParseError(Exception):
"""Raised when a string unit name is not parseable as a valid unit
Example
-------
>>> from unyt import Unit
>>> Unit('hello')\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.UnitParseError: Could not find unit symbol
'hello' in the provided symbols.
"""
pass
[docs]class IllDefinedUnitSystem(Exception):
"""Raised when the dimensions of the base units of a unit system are
inconsistent.
Example
-------
>>> from unyt.unit_systems import UnitSystem
>>> UnitSystem('atomic', 'nm', 'fs', 'nK', 'rad')\
# doctest: +IGNORE_EXCEPTION_DETAIL +NORMALIZE_WHITESPACE
Traceback (most recent call last):
...
unyt.exceptions.IllDefinedUnitSystem: Cannot create unit system
with inconsistent mapping from
dimensions to units. Received:
OrderedDict([((length), nm), ((mass), fs), ((time), nK),
((temperature), rad), ((angle), rad),
((current_mks), A), ((luminous_intensity), cd)])
"""
def __init__(self, units_map):
self.units_map = units_map
def __str__(self):
return (
"Cannot create unit system with inconsistent mapping from "
"dimensions to units. Received:\n%s" % self.units_map
)
