zdf1 = bcolz.ctable.fromdataframe(df1)
zdf2 = bcolz.ctable.fromdataframe(df2)
merged = list(joinz(1, zdf1.iter(), 0, zdf2.iter()))
zdf3 = bcolz.fromiter((a[0] + a[1] for a in merged), dtype=new_dtypes,
    count=len(merged))
Python bcolz, как объединить две ctables