Larger than memory plotting: how to set initial slice to plot

HoloViews
8

Okay, I think this works

import h5py
import numpy as np
import panel as pn
import xarray as xr
import holoviews as hv
import dask.array as da
from holoviews.operation.datashader import rasterize, shade
hv.extension('bokeh', logo=False)

f = h5py.File('data.h5', "r")
full_data = da.from_array(f['data'], chunks=(60*60, 2401), name=False)
da = xr.DataArray(
    full_data,
    dims=("x", "y"),
    coords={"x": np.arange(full_data.shape[0]), "y": np.arange(full_data.shape[1])},
)

class BigSpectrogram():
    def points(self, x_range, y_range):
        print(x_range, y_range)
        data = da.sel(x=slice(*x_range), y=slice(*y_range)).compute()
        image = hv.Image(data)
        return image

    def view(self,**kwargs):
        range_xy = hv.streams.RangeXY(x_range=(0, 3600), y_range=(0, 2401))
        points = hv.DynamicMap(self.points, streams=[range_xy])
        agg = rasterize(points)
        return agg

spectrogram = BigSpectrogram()
pn.Row(spectrogram.view()).servable()