melt-and-stack

Untitled2.ipynb

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      "source": "import pandas as pd",
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      "cell_type": "code",
      "source": "field = pd.DataFrame([['x', 'y'],\n                      ['z', 't']], columns=['a', 'b'])",
      "execution_count": 2,
      "outputs": []
    },
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      "cell_type": "code",
      "source": "field",
      "execution_count": 3,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 3,
          "data": {
            "text/plain": "   a  b\n0  x  y\n1  z  t",
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    {
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      "cell_type": "code",
      "source": "stacked = field.stack()",
      "execution_count": 6,
      "outputs": []
    },
    {
      "metadata": {
        "trusted": true
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      "cell_type": "code",
      "source": "stacked",
      "execution_count": 7,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 7,
          "data": {
            "text/plain": "0  a    x\n   b    y\n1  a    z\n   b    t\ndtype: object"
          },
          "metadata": {}
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      ]
    },
    {
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        "trusted": true
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      "cell_type": "code",
      "source": "stacked.index",
      "execution_count": 8,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 8,
          "data": {
            "text/plain": "MultiIndex(levels=[[0, 1], ['a', 'b']],\n           codes=[[0, 0, 1, 1], [0, 1, 0, 1]])"
          },
          "metadata": {}
        }
      ]
    },
    {
      "metadata": {
        "trusted": true
      },
      "cell_type": "code",
      "source": "stacked.index.to_list()",
      "execution_count": 9,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 9,
          "data": {
            "text/plain": "[(0, 'a'), (0, 'b'), (1, 'a'), (1, 'b')]"
          },
          "metadata": {}
        }
      ]
    },
    {
      "metadata": {
        "trusted": true
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      "cell_type": "code",
      "source": "stacked[(0, 'a')]",
      "execution_count": 11,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 11,
          "data": {
            "text/plain": "'x'"
          },
          "metadata": {}
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      ]
    },
    {
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      "cell_type": "code",
      "source": "stacked[0, 'a'] # здесь неявно создаётся кортеж `(0, 'a')`",
      "execution_count": 13,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 13,
          "data": {
            "text/plain": "'x'"
          },
          "metadata": {}
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      ]
    },
    {
      "metadata": {
        "trusted": true
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      "cell_type": "code",
      "source": "melted = field.melt()",
      "execution_count": 14,
      "outputs": []
    },
    {
      "metadata": {
        "trusted": true
      },
      "cell_type": "code",
      "source": "melted",
      "execution_count": 15,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 15,
          "data": {
            "text/plain": "  variable value\n0        a     x\n1        a     z\n2        b     y\n3        b     t",
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      "cell_type": "code",
      "source": "stacked.reset_index(level=1)",
      "execution_count": 17,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 17,
          "data": {
            "text/plain": "  level_1  0\n0       a  x\n0       b  y\n1       a  z\n1       b  t",
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