Source code for impy.utils.slicer

from __future__ import annotations
import re
from functools import lru_cache
from typing import Any, Mapping
from .._types import Slices
from ..axes import Slicer, Axes

__all__ = ["str_to_slice", "axis_targeted_slicing", "solve_slicer"]

def _range_to_list(v: str) -> list[int]:
    """
    "1,3,5" -> [1,3,5]
    "2,4:6,9" -> [2,4,5,6,9]
    """
    if ":" in v:
        s, e = v.split(":")
        return list(range(int(s), int(e)))
    else:
        return [int(v)]

def _int_or_none(v: str) -> int | None:
    if v:
        return int(v)
    else:
        return None
    
[docs]def str_to_slice(v: str) -> list[int] | slice | int: v = re.sub(" ", "", v) if "," in v: sl = sum((_range_to_list(v) for v in v.split(",")), []) elif ":" in v: sl = slice(*map(_int_or_none, v.split(":"))) else: sl = int(v) return sl
[docs]@lru_cache def axis_targeted_slicing(axes: tuple[str, ...], string: str) -> Slices: """ Make a conventional slices from an axis-targeted slicing string. Parameters ---------- ndim : int Number of dimension of the array which will be sliced. axes : str Axes of input ndarray. string : str Axis-targeted slicing string. If an axis that does not exist in `axes` is contained, this function will raise ValueError. Returns ------- slices """ keylist = re.sub(" ", "", string).split(";") dict_slicer: dict[str, Any] = {} for k in keylist: if k.count("=") != 1: raise ValueError(f"Informal axis-targeted slicing: {k!r}.") axis, sl_str = k.split("=") try: sl = str_to_slice(sl_str) except ValueError: raise ValueError(f"Informal axis-targeted slicing: {k!r}.") else: dict_slicer[axis] = sl return dict_to_slice(dict_slicer, axes)
def dict_to_slice(sl: dict[str, Any], axes: tuple[str, ...]): sl_list = [slice(None)] * len(axes) for k, v in sl.items(): idx = axes.index(k) sl_list[idx] = v return tuple(sl_list)
[docs]def solve_slicer(key: Any, axes: Axes) -> Slices: if isinstance(key, str): key = axis_targeted_slicing(tuple(axes), key) elif isinstance(key, (Mapping, Slicer)): key = axes.create_slice(key) return key