def __getitem__(self, item):
# At first, we will only implement this as accepting a slice that is
# (optionally) unitful corresponding to a specific set of coordinates
# that result in a rectangular prism or a slice.
try:
return self.all_data[item]
except (TypeError, YTFieldNotParseable):
pass
if isinstance(item, slice):
if obj_length(item.start) == 3 and obj_length(item.stop) == 3:
# This is for a ray that is not orthogonal to an axis.
# it's straightforward to do this, so we create a ray
# and drop out here.
return self._create_ray(item)
else:
# This is for the case where we give a slice as an index; one
# possible use case of this would be where we supply something
# like ds.r[::256j] . This would be expanded, implicitly into
# ds.r[::256j, ::256j, ::256j]. Other cases would be if we do
# ds.r[0.1:0.9] where it will be expanded along all dimensions.
item = tuple(item for _ in range(self.ds.dimensionality))
if item is Ellipsis:
item = (Ellipsis, )
# from this point, item is implicitly assumed to be iterable
if Ellipsis in item:
# expand "..." into the appropriate number of ":"
item = list(item)
idx = item.index(Ellipsis)
item.pop(idx)
if Ellipsis in item:
# this error mimics numpy's
raise IndexError(
"an index can only have a single ellipsis ('...')")
while len(item) < self.ds.dimensionality:
item.insert(idx, slice(None))
if len(item) != self.ds.dimensionality:
# Not the right specification, and we don't want to do anything
# implicitly. Note that this happens *after* the implicit expansion
# of a single slice.
raise YTDimensionalityError(len(item), self.ds.dimensionality)
# OK, now we need to look at our slices. How many are a specific
# coordinate?
nslices = sum(isinstance(v, slice) for v in item)
if nslices == 0:
return self._create_point(item)
elif nslices == 1:
return self._create_ortho_ray(item)
elif nslices == 2:
return self._create_slice(item)
else:
if all(s.start is s.stop is s.step is None for s in item):
return self.all_data
return self._create_region(item)
def __getitem__(self, item):
# At first, we will only implement this as accepting a slice that is
# (optionally) unitful corresponding to a specific set of coordinates
# that result in a rectangular prism or a slice.
if isinstance(item, string_types):
# This is some field; we will instead pass this back to the
# all_data object.
return self.all_data[item]
if isinstance(item, tuple) and isinstance(item[1], string_types):
return self.all_data[item]
if isinstance(item, slice):
if obj_length(item.start) == 3 and obj_length(item.stop) == 3:
# This is for a ray that is not orthogonal to an axis.
# it's straightforward to do this, so we create a ray
# and drop out here.
return self._create_ray(item)
else:
# This is for the case where we give a slice as an index; one
# possible use case of this would be where we supply something
# like ds.r[::256j] . This would be expanded, implicitly into
# ds.r[::256j, ::256j, ::256j]. Other cases would be if we do
# ds.r[0.1:0.9] where it will be expanded along three dimensions.
item = (item, item, item)
if len(item) != self.ds.dimensionality:
# Not the right specification, and we don't want to do anything
# implicitly. Note that this happens *after* the implicit expansion
# of a single slice.
raise YTDimensionalityError(len(item), self.ds.dimensionality)
if self.ds.dimensionality != 3:
# We'll pass on this for the time being.
raise RuntimeError
# OK, now we need to look at our slices. How many are a specific
# coordinate?
nslices = sum(isinstance(v, slice) for v in item)
if nslices == 0:
return self._create_point(item)
elif nslices == 1:
return self._create_ortho_ray(item)
elif nslices == 2:
return self._create_slice(item)
else:
if all(s.start is s.stop is s.step is None for s in item):
return self.all_data
return self._create_region(item)
def print_all_fields(fl):
for fn in sorted(fl):
df = fl[fn]
f = df._function
s = f"{df.name}"
print(s)
print("^" * len(s))
print()
if obj_length(df.units) > 0:
# Most universal fields are in CGS except for these special fields
if df.name[1] in [
"particle_position",
"particle_position_x",
"particle_position_y",
"particle_position_z",
"entropy",
"kT",
"metallicity",
"dx",
"dy",
"dz",
"cell_volume",
"x",
"y",
"z",
]:
print(f" * Units: :math:`{fix_units(df.units)}`")
else:
print(
f" * Units: :math:`{fix_units(df.units, in_cgs=True)}`")
print(f" * Sampling Method: {df.sampling_type}")
print()
print("**Field Source**")
print()
if f == NullFunc:
print("No source available.")
print()
continue
else:
print(".. code-block:: python")
print()
for line in inspect.getsource(f).split("\n"):
print(" " + line)
print()
def add_field(
self,
name: Tuple[str, str],
function: Callable,
sampling_type: str,
*,
alias: Optional[DerivedField] = None,
force_override: bool = False,
**kwargs,
) -> None:
"""
Add a new field, along with supplemental metadata, to the list of
available fields. This respects a number of arguments, all of which
are passed on to the constructor for
:class:`~yt.data_objects.api.DerivedField`.
Parameters
----------
name : tuple[str, str]
field (or particle) type, field name
function : callable
A function handle that defines the field. Should accept
arguments (field, data)
sampling_type: str
"cell" or "particle" or "local"
force_override: bool
If False (default), an error will be raised if a field of the same name already exists.
alias: DerivedField (optional):
existing field to be aliased
units : str
A plain text string encoding the unit. Powers must be in
python syntax (** instead of ^). If set to "auto" the units
will be inferred from the return value of the field function.
take_log : bool
Describes whether the field should be logged
validators : list
A list of :class:`FieldValidator` objects
vector_field : bool
Describes the dimensionality of the field. Currently unused.
display_name : str
A name used in the plots
"""
# Handle the case where the field has already been added.
if not force_override and name in self:
return
kwargs.setdefault("ds", self.ds)
if not isinstance(function, Callable): # type: ignore [arg-type]
# type-checking is disabled because of https://github.com/python/mypy/issues/11071
# this is compatible with lambdas and functools.partial objects
raise TypeError(
f"Expected a callable object, got {function} with type {type(function)}"
)
# lookup parameters that do not have default values
fparams = inspect.signature(function).parameters
nodefaults = tuple(p.name for p in fparams.values()
if p.default is p.empty)
if nodefaults != ("field", "data"):
raise TypeError(
f"Received field function {function} with invalid signature. "
f"Expected exactly 2 positional parameters ('field', 'data'), got {nodefaults!r}"
)
if any(fparams[name].kind == fparams[name].KEYWORD_ONLY
for name in ("field", "data")):
raise TypeError(
f"Received field function {function} with invalid signature. "
"Parameters 'field' and 'data' must accept positional values "
"(they cannot be keyword-only)")
sampling_type = self._sanitize_sampling_type(sampling_type)
if (not isinstance(name, str) and obj_length(name) == 2
and all(isinstance(e, str) for e in name)):
self[name] = DerivedField(name,
sampling_type,
function,
alias=alias,
**kwargs)
else:
raise ValueError(
f"Expected name to be a tuple[str, str], got {name}")
