notebook-extra-loading-saving-arrays.ipynb

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   "source": [
    "### Extra: loading and saving arrays"
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   "source": [
    "import numpy as np"
   ]
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    "Simple, with ```np.load``` and ```np.save```. File contains only *one* array and saves in binary."
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   "source": [
    "a = np.random.randint(1, 10, (100, 100))\n",
    "\n",
    "np.save('data/random', a)\n"
   ]
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   "source": [
    "np.save('data/random_notpickled', a, allow_pickle=False)"
   ]
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   "cell_type": "markdown",
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   "source": [
    "We can also save array as text file, not binary."
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   "source": [
    "np.savetxt('data/random_as_text.txt', a)"
   ]
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   "cell_type": "markdown",
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   "source": [
    "Q: Compare the file sizes, notice a difference?"
   ]
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   "source": [
    "Loading with ```np.load```"
   ]
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     "data": {
      "text/plain": [
       "array([[5, 4, 1, ..., 1, 6, 7],\n",
       "       [2, 3, 4, ..., 1, 3, 1],\n",
       "       [4, 4, 1, ..., 2, 9, 4],\n",
       "       ...,\n",
       "       [6, 2, 5, ..., 4, 6, 3],\n",
       "       [7, 3, 6, ..., 6, 5, 5],\n",
       "       [5, 4, 9, ..., 2, 6, 9]])"
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   "source": [
    "np.load('data/random.npy')"
   ]
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   "source": [
    "For **several** arrays: ```np.savez``` saves in ```.npz``` format."
   ]
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   "source": [
    "b = np.random.randint(1, 10, (100, 100))\n",
    "\n",
    "np.savez('data/arrays.npz', x=a, y=b)"
   ]
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     "data": {
      "text/plain": [
       "['x', 'y']"
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     "execution_count": 7,
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   "source": [
    "data = np.load('data/arrays.npz')\n",
    "data.files"
   ]
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       "array([[5, 4, 1, ..., 1, 6, 7],\n",
       "       [2, 3, 4, ..., 1, 3, 1],\n",
       "       [4, 4, 1, ..., 2, 9, 4],\n",
       "       ...,\n",
       "       [6, 2, 5, ..., 4, 6, 3],\n",
       "       [7, 3, 6, ..., 6, 5, 5],\n",
       "       [5, 4, 9, ..., 2, 6, 9]])"
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    "data['x']"
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