py: read postprocess grid

read_grid.py

import numpy as np
import xarray as xa
import h5py as h5

PATH_IN = "/fred/oz078/smutch/intensity_mapping/baseline/imapping_testrun/HIMass_grids.h5"
SNAPSHOT = 250  # z=0

with h5.File(PATH_IN, "r") as fp:
    ds = fp[f"Snap{SNAPSHOT:03d}"]
    box_size = ds.attrs["box_size"][:]
    dim = ds.attrs["dim"][:]
    grid = xa.DataArray(
        ds[:],
        coords=[np.linspace(0, bs, d) for bs, d in zip(box_size, dim)],
        dims=list("xyz"),
        name="HIMass",
    )

grid = grid.where(np.isfinite(grid), np.nan)