src/retrieval.py

from pathlib import Path
from typing import Optional

import numpy as np
import pyarrow as pa


class ArrowMetadataProvider:
    """The arrow metadata provider provides metadata from contiguous ids using arrow.

    Code taken from: https://github.dev/rom1504/clip-retrieval
    """

    def __init__(self, arrow_folder: str):
        arrow_files = [str(a) for a in sorted(Path(arrow_folder).glob("**/*")) if a.is_file()]
        self.table = pa.concat_tables(
            [
                pa.ipc.RecordBatchFileReader(pa.memory_map(arrow_file, "r")).read_all()
                for arrow_file in arrow_files
            ]
        )

    def get(self, ids: np.ndarray, cols: Optional[list] = None):
        """Implement the get method from the arrow metadata provide, get metadata from ids."""
        if cols is None:
            cols = self.table.schema.names
        else:
            cols = list(set(self.table.schema.names) & set(cols))
        t = pa.concat_tables([self.table[i:j] for i, j in zip(ids, ids + 1)])
        return t.select(cols).to_pandas().to_dict("records")