blosc2.Proxy.afetch#
- async Proxy.afetch(item: slice | list[slice] = None) NDArray | SChunk #
Get the container used as cache with the requested data updated in an asynchronous way.
- Parameters:
item¶ (slice or list of slices, optional) – If not None, only the chunks that intersect with the slices in items will be retrieved if they have not been already.
- Returns:
out – The local container used to cache the already requested data.
- Return type:
Notes
This method is only available if the ProxySource or ProxyNDSource have an async aget_chunk method.
Examples
>>> import numpy as np >>> import blosc2 >>> import asyncio >>> from blosc2 import ProxyNDSource >>> class MyProxySource(ProxyNDSource): >>> def __init__(self, data): >>> # If the next source is multidimensional, it must have the attributes: >>> self.data = data >>> f"Data shape: {self.shape}, Chunks: {self.chunks}" >>> f"Blocks: {self.blocks}, Dtype: {self.dtype}" >>> @property >>> def shape(self): >>> return self.data.shape >>> @property >>> def chunks(self): >>> return self.data.chunks >>> @property >>> def blocks(self): >>> return self.data.blocks >>> @property >>> def dtype(self): >>> return self.data.dtype >>> # This method must be present >>> def get_chunk(self, nchunk): >>> return self.data.get_chunk(nchunk) >>> # This method is optional >>> async def aget_chunk(self, nchunk): >>> await asyncio.sleep(0.1) # Simulate an asynchronous operation >>> return self.data.get_chunk(nchunk) >>> data = np.arange(20).reshape(4, 5) >>> chunks = [2, 5] >>> blocks = [1, 5] >>> data = blosc2.asarray(data, chunks=chunks, blocks=blocks) >>> source = MyProxySource(data) >>> proxy = blosc2.Proxy(source) >>> async def fetch_data(): >>> # Fetch a slice of the data from the proxy asynchronously >>> slice_data = await proxy.afetch(slice(0, 2)) >>> # Note that only data fetched is shown, the rest is uninitialized >>> slice_data[:] >>> asyncio.run(fetch_data()) >>> # Using getitem to get a slice of the data >>> result = proxy[1:2, 1:3] >>> f"Proxy getitem: {result}" Data shape: (4, 5), Chunks: (2, 5) Blocks: (1, 5), Dtype: int64 [[0 1 2 3 4] [5 6 7 8 9] [0 0 0 0 0] [0 0 0 0 0]] Proxy getitem: [[6 7]]