import numpy
from typing import Any, Optional, Tuple, List, NamedTuple
from collections.abc import Collection
from .helpers import check_arg
from .naming import natural_varname
[docs]class MaskedVarInfo(NamedTuple):
basename: str
selector: str = ""
mask: Optional[numpy.ndarray] = None
@property
def fullname(self) -> bool:
return f"{self.basename}{self.selector}"
[docs]def find_selector(expression: str) -> Tuple[str, str]:
"""Decompose a string expression into `basename` and `selector`,
where `selector` is a suitable mask expression for an array.
Parameters:
-----------
expression [str]: the expression to be parsed.
Returns:
--------
baseline, selector [str, str]
"""
expression = expression.strip()
left_bracket, right_bracket = brackets = tuple("[]")
nl = nr = il = 0
basename, selector = expression, "" # default
if expression.endswith(right_bracket):
i = len(expression)
for char in reversed(expression):
i -= 1
if char == right_bracket:
nr += 1
elif char == left_bracket:
nl += 1
if nl == nr:
prev_char = expression[i - 1] if i > 0 else None
if prev_char not in brackets:
il = i
break
elif expression.endswith(left_bracket):
nl, nr = 1, 0
balanced = (nl == nr)
if not balanced:
raise ValueError(f"Bracket mismatch in {expression!s}")
if il > 0 or expression.startswith(left_bracket):
basename = expression[:il]
selector = expression[il:]
return basename, selector
# TODO should we reintegrate it as Boundary method as it is now the only used place
[docs]def get_indices(system: "cosapp.base.System", name: str) -> MaskedVarInfo:
"""Decompose a variable specification into its base name and mask.
Parameters
----------
system : System
System to which variable belongs
name : str
Variable specification (variable name + optional array mask, if required)
Returns
-------
MaskedVarInfo (named tuple):
- basename [str]: variable name
- selector [str]: array selector
- mask [numpy.ndarray[bool]]: mask (if array) or `None`
"""
check_arg(name, 'name', str)
name = natural_varname(name)
def check_eval(attribute: str) -> Any:
try:
value = eval(f"s.{attribute}", {}, {"s": system})
except AttributeError as error:
error.args = (f"{attribute!r} is not known in {system.name}",)
raise
except Exception as error:
error.args = (f"Can't evaluate {attribute!r} in {system.name}",)
raise
else:
return value
try:
basename, selector = find_selector(name)
except ValueError as error:
raise SyntaxError(error)
value = check_eval(basename)
mask = None
if selector:
# Check value is an array
if not (
isinstance(value, numpy.ndarray)
and numpy.issubdtype(value.dtype, numpy.number)
and value.size > 1
):
raise TypeError(
f"Only non-empty numpy arrays can be partially selected; got '{system.name}.{name}'."
)
mask = numpy.zeros_like(value, dtype=bool)
# Set mask from selector string
try:
exec(f"mask{selector} = True", {}, {"mask": mask})
except (SyntaxError, IndexError) as error:
varname = f"{system.name}.{basename}"
error.args = (
f"Invalid selector {selector!r} for variable {varname!r}: {error!s}",
)
raise
elif isinstance(value, Collection) and not isinstance(value, str):
mask = numpy.ones_like(value, dtype=bool)
return MaskedVarInfo(basename, selector, mask)
[docs]def multi_split(expression: str, separators: List[str]) -> Tuple[List[str], List[str]]:
"""Extension of `str.split`, accounting for more than one split separators.
Parameters:
-----------
- expression [str]:
Expression to be split.
- separators [List[str]]:
List of separators.
Returns:
--------
- expressions [List[str]]:
List of n split expressions.
- separators [List[str]]:
Sequence of (n - 1) separators between split expressions.
Examples:
---------
>>> multi_split('a+b-c-d+e', list('+-'))
['a', 'b', 'c', 'd', 'e'], ['+', '-', '-', '+']
"""
expressions = [expression]
sep_list = []
for separator in set(separators):
new_list = []
shift = 0
for i, expression in enumerate(expressions):
sublist = expression.split(separator)
n_hits = len(sublist) - 1
new_list.extend(sublist)
if n_hits > 0:
j = i + shift
shift += n_hits
sep_list = sep_list[:j] + [separator] * n_hits + sep_list[j:]
expressions = list(map(str.strip, new_list))
return expressions, sep_list
