create fvecs for github.com ZJULearning AtSNE

import numpy as np
import sys
import struct

dim = 50
a = np.load('stacked-vecs-{}.npy'.format(dim))

with open('stacked.fvecs', 'wb') as out:
  for i in a:
    line = [float(j) for j in i]
    out.write(struct.pack('=I', dim))
    out.write(struct.pack('={}{}'.format(dim, 'f'), *line))