Numpy types ordering regarding their maximum values

types_max_values_ordering.ipynb

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  {
   "cell_type": "markdown",
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   "source": [
    "I'm doing some type optimization and it raised me a question: how int and float types can be ordered with respect to their maximum values?"
   ]
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   "source": [
    "import numpy as np"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "From [this numpy doc](https://docs.scipy.org/doc/numpy-1.10.1/reference/arrays.scalars.html), I can reach the following types:"
   ]
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   "outputs": [],
   "source": [
    "int_types = [np.int8, np.int16, np.int32, np.int64]\n",
    "float_types = [np.float16, np.float32, np.float64]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Using numpy's [iinfo](https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.iinfo.html) and [iinfo](https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.finfo.html), I can get their maximum values."
   ]
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   "cell_type": "code",
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   "outputs": [],
   "source": [
    "int_maxes = map(lambda x: np.iinfo(x).max, int_types)\n",
    "float_maxes = map(lambda x: np.finfo(x).max, float_types)"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "Putting all together:"
   ]
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    {
     "data": {
      "text/plain": [
       "[(numpy.int8, 127),\n",
       " (numpy.int16, 32767),\n",
       " (numpy.int32, 2147483647),\n",
       " (numpy.int64, 9223372036854775807),\n",
       " (numpy.float16, 65504.0),\n",
       " (numpy.float32, 3.4028235e+38),\n",
       " (numpy.float64, 1.7976931348623157e+308)]"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "maxes = list(zip(int_types, int_maxes)) + list(zip(float_types, float_maxes))\n",
    "maxes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "And sorting (biggest to smallest):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "[(numpy.float64, 1.7976931348623157e+308),\n",
       " (numpy.float32, 3.4028235e+38),\n",
       " (numpy.int64, 9223372036854775807),\n",
       " (numpy.int32, 2147483647),\n",
       " (numpy.float16, 65504.0),\n",
       " (numpy.int16, 32767),\n",
       " (numpy.int8, 127)]"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sorted(maxes, key=lambda x: x[1], reverse=True)"
   ]
  }
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