edsnlp.utils.filter

get_sort_key(span)

Returns the sort key for filtering spans.

PARAMETER	DESCRIPTION
span	Span to sort. TYPE: Span

RETURNS	DESCRIPTION
key	Sort key. TYPE: Tuple(int, int)

Source code in edsnlp/utils/filter.py

def get_sort_key(span: Span) -> Tuple[int, int]:
    """
    Returns the sort key for filtering spans.

    Parameters
    ----------
    span : Span
        Span to sort.

    Returns
    -------
    key : Tuple(int, int)
        Sort key.
    """
    return span.end - span.start, -span.start

filter_spans(spans, label_to_remove=None, return_discarded=False)

Re-definition of spacy's filtering function, that returns discarded spans as well as filtered ones.

Can also accept a label_to_remove argument, useful for filtering out pseudo cues. If set, results can contain overlapping spans: only spans overlapping with excluded labels are removed. The main expected use case is for pseudo-cues.

The spaCy documentation states:

Filter a sequence of spans and remove duplicates or overlaps. Useful for creating named entities (where one token can only be part of one entity) or when merging spans with Retokenizer.merge. When spans overlap, the (first) longest span is preferred over shorter spans.

Filtering out spans

If the label_to_remove argument is supplied, it might be tempting to filter overlapping spans that are not part of a label to remove.

The reason we keep all other possibly overlapping labels is that in qualifier pipelines, the same cue can precede and follow a marked entity. Hence we need to keep every example.

PARAMETER	DESCRIPTION
spans	Spans to filter. TYPE: List[Span]
return_discarded	Whether to return discarded spans. TYPE: bool DEFAULT: False
label_to_remove	Label to remove. If set, results can contain overlapping spans. TYPE: str, optional DEFAULT: None

RETURNS	DESCRIPTION
results	Filtered spans TYPE: List[Span]
discarded	Discarded spans TYPE: List[Span], optional

Source code in edsnlp/utils/filter.py

def filter_spans(
    spans: Iterable[Union["Span", Tuple["Span", Any]]],
    label_to_remove: Optional[str] = None,
    return_discarded: bool = False,
) -> Union[List["Span"], Tuple[List["Span"], List["Span"]]]:
    """
    Re-definition of spacy's filtering function, that returns discarded spans
    as well as filtered ones.

    Can also accept a `label_to_remove` argument, useful for filtering out
    pseudo cues. If set, `results` can contain overlapping spans: only
    spans overlapping with excluded labels are removed. The main expected
    use case is for pseudo-cues.

    !!! note ""

        The **spaCy documentation states**:

        > Filter a sequence of spans and remove duplicates or overlaps.
        > Useful for creating named entities (where one token can only
        > be part of one entity) or when merging spans with
        > `Retokenizer.merge`. When spans overlap, the (first)
        > longest span is preferred over shorter spans.

    !!! danger "Filtering out spans"

        If the `label_to_remove` argument is supplied, it might be tempting to
        filter overlapping spans that are not part of a label to remove.

        The reason we keep all other possibly overlapping labels is that in qualifier
        pipelines, the same cue can precede **and** follow a marked entity.
        Hence we need to keep every example.

    Parameters
    ----------
    spans : List[Span]
        Spans to filter.
    return_discarded : bool
        Whether to return discarded spans.
    label_to_remove : str, optional
        Label to remove. If set, results can contain overlapping spans.

    Returns
    -------
    results : List[Span]
        Filtered spans
    discarded : List[Span], optional
        Discarded spans
    """
    sorted_spans = sorted(spans, key=get_sort_key, reverse=True)
    result = []
    discarded = []
    seen_tokens = set()
    for span in sorted_spans:
        # Check for end - 1 here because boundaries are inclusive
        if span.start not in seen_tokens and span.end - 1 not in seen_tokens:
            if label_to_remove is None or span.label_ != label_to_remove:
                result.append(span)
            if label_to_remove is None or span.label_ == label_to_remove:
                seen_tokens.update(range(span.start, span.end))
        elif label_to_remove is None or span.label_ != label_to_remove:
            discarded.append(span)

    result = sorted(result, key=lambda span: span.start)
    discarded = sorted(discarded, key=lambda span: span.start)

    if return_discarded:
        return result, discarded

    return result

consume_spans(spans, filter, second_chance=None)

Consume a list of span, according to a filter.

Warning

This method makes the hard hypothesis that:

1. Spans are sorted.
2. Spans are consumed in sequence and only once.

The second item is problematic for the way we treat long entities, hence the second_chance parameter, which lets entities be seen more than once.

PARAMETER	DESCRIPTION
spans	List of spans to filter TYPE: List of spans
filter	Filtering function. Should return True when the item is to be included. TYPE: Callable
second_chance	Optional list of spans to include again (useful for long entities), by default None TYPE: List of spans, optional DEFAULT: None

RETURNS	DESCRIPTION
matches	List of spans consumed by the filter. TYPE: List of spans
remainder	List of remaining spans in the original spans parameter. TYPE: List of spans

Source code in edsnlp/utils/filter.py

def consume_spans(
    spans: List[Span],
    filter: Callable,
    second_chance: Optional[List[Span]] = None,
) -> Tuple[List[Span], List[Span]]:
    """
    Consume a list of span, according to a filter.

    !!! warning
        This method makes the hard hypothesis that:

        1. Spans are sorted.
        2. Spans are consumed in sequence and only once.

        The second item is problematic for the way we treat long entities,
        hence the `second_chance` parameter, which lets entities be seen
        more than once.

    Parameters
    ----------
    spans : List of spans
        List of spans to filter
    filter : Callable
        Filtering function. Should return True when the item is to be included.
    second_chance : List of spans, optional
        Optional list of spans to include again (useful for long entities),
        by default None

    Returns
    -------
    matches : List of spans
        List of spans consumed by the filter.
    remainder : List of spans
        List of remaining spans in the original `spans` parameter.
    """

    if not second_chance:
        second_chance = []
    else:
        second_chance = [m for m in second_chance if filter(m)]

    if not spans:
        return second_chance, []

    for i, span in enumerate(spans):
        if not filter(span):
            break
        else:
            i += 1

    matches = spans[:i]
    remainder = spans[i:]

    matches.extend(second_chance)

    return matches, remainder

get_spans(spans, label)

Extracts spans with a given label. Prefer using hash label for performance reasons.

PARAMETER	DESCRIPTION
spans	List of spans to filter. TYPE: List[Span]
label	Label to filter on. TYPE: Union[int, str]

RETURNS	DESCRIPTION
List[Span]	Filtered spans.

Source code in edsnlp/utils/filter.py

def get_spans(spans: List[Span], label: Union[int, str]) -> List[Span]:
    """
    Extracts spans with a given label.
    Prefer using hash label for performance reasons.

    Parameters
    ----------
    spans : List[Span]
        List of spans to filter.
    label : Union[int, str]
        Label to filter on.

    Returns
    -------
    List[Span]
        Filtered spans.
    """
    if isinstance(label, int):
        return [span for span in spans if span.label == label]
    else:
        return [span for span in spans if span.label_ == label]