import numpy as np

def load_cache(infile, nsamples=None):
    cache = dict()
    with np.load(infile) as data:
        array = data['arr_0'][0]
        for i,(x,y) in enumerate(array):
            cache[x] = y
            if i == nsamples:
                break

    return cache

def save_cache(cache, outfile):
    np.savez(outfile,[np.array(cache)])