1.5 numpy通用函数和统计方法.ipynb

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   "cell_type": "code",
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   "id": "37186df0",
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   "source": [
    "import numpy as np"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "41c18100",
   "metadata": {},
   "source": [
    "# 通用函数"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "b126c0cb",
   "metadata": {},
   "outputs": [],
   "source": [
    "a = np.arange(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "08db5469",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "0e60b3a6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0.        , 1.        , 1.41421356, 1.73205081, 2.        ,\n",
       "       2.23606798, 2.44948974, 2.64575131, 2.82842712, 3.        ])"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.sqrt(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "ef161b25",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 0.        ,  0.84147098,  0.90929743,  0.14112001, -0.7568025 ,\n",
       "       -0.95892427, -0.2794155 ,  0.6569866 ,  0.98935825,  0.41211849])"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.sin(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "bf4bf4f1",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 1.        ,  0.54030231, -0.41614684, -0.9899925 , -0.65364362,\n",
       "        0.28366219,  0.96017029,  0.75390225, -0.14550003, -0.91113026])"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.cos(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "a8c713d9",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 0,  1,  4,  9, 16, 25, 36, 49, 64, 81])"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a**2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "8637b2e2",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([  0,   1,   8,  27,  64, 125, 216, 343, 512, 729], dtype=int32)"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a**3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "81f4ed7d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "ff1c1f3d",
   "metadata": {},
   "outputs": [],
   "source": [
    "b = np.arange(10, 0, -1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "598f44fe",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([10,  9,  8,  7,  6,  5,  4,  3,  2,  1])"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "b"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "cd19440c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([10,  9,  8,  7,  6,  5,  6,  7,  8,  9])"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.maximum(a,b) # 对比两个数组，取出较大值"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "0f88ed47",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([-10,  -8,  -6,  -4,  -2,   0,   2,   4,   6,   8])"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a-b"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "aab43528",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([-10,  -8,  -6,  -4,  -2,   0,   2,   4,   6,   8])"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.subtract(a,b)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "d3a7ce6d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a[a >= b]  # a中大于b的元素"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e07e09fa",
   "metadata": {},
   "source": [
    "# 统计方法"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "id": "7739d113",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "id": "2d557cf2",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.5"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.mean(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "id": "c00bcc84",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.5"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a.mean()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "id": "ac5e0d3d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "45"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.sum(a)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "id": "c2d1bf6c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "45"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a.sum()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "id": "391030e8",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a1 = a.reshape(2,5)\n",
    "a1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "id": "a527a1f6",
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     "data": {
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       "array([2., 7.])"
      ]
     },
     "execution_count": 29,
     "metadata": {},
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    }
   ],
   "source": [
    "a1.mean(axis=1)  # 沿着行操作，得到一个列，列变化，axis=1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "id": "ead48023",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([2.5, 3.5, 4.5, 5.5, 6.5])"
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a1.mean(axis=0)  # 沿着列操作，得到一个行，行变化，axis=0 "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "id": "926c8170",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 5,  7,  9, 11, 13])"
      ]
     },
     "execution_count": 31,
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   "source": [
    "a1.sum(0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "id": "107485c6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 32,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "id": "9b19006d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 5])"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.min(a1, axis=1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "id": "28cd91fc",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.max(a1, axis=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "id": "a9c2380a",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([2.5, 2.5, 2.5, 2.5, 2.5])"
      ]
     },
     "execution_count": 36,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.std(a1, axis=0)  # 求方差"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 37,
   "id": "1a8d8d81",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([1.41421356, 1.41421356])"
      ]
     },
     "execution_count": 37,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.median(a1, axis=1)  # 中位值"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "46c14c7f",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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