26 lines
863 B
Python
26 lines
863 B
Python
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from typing import Callable, List, Tuple, TypeVar, cast
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from ..config import registry
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from ..model import Model
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from ..types import ArrayXd, ListXd, Ragged
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InT = TypeVar("InT", bound=ListXd)
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OutT = Ragged
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@registry.layers("list2ragged.v1")
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def list2ragged() -> Model[InT, OutT]:
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"""Transform sequences to ragged arrays if necessary and return the ragged
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array. If sequences are already ragged, do nothing. A ragged array is a
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tuple (data, lengths), where data is the concatenated data.
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"""
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return Model("list2ragged", forward)
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def forward(model: Model[InT, OutT], Xs: InT, is_train: bool) -> Tuple[OutT, Callable]:
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def backprop(dYr: OutT) -> InT:
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return cast(InT, model.ops.unflatten(dYr.data, dYr.lengths))
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lengths = model.ops.asarray1i([len(x) for x in Xs])
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return Ragged(model.ops.flatten(Xs), lengths), backprop
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