I'm reading in large sets of data from an .h5 file, (200,000 points per dataset) and I currently don't need all of it so what I've been doing is reading in the data, then truncating it after.

Is there a way to only read the first X items of an h5 dataset?

解决方案

Use this...

import numpy as np

import h5py

filename = 'file.hdf5'

f = h5py.File(filename, 'r')

key = list(f.keys())[0]

data = list(f[key][1])

Indexing may vary for key and f[key], where [0] is an arbitrary dataset of file.hdf5 and [1] is just an arbitrary column I grabbed.