Numpy_Coding_Question.ipynb

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    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1.21.5\n"
     ]
    }
   ],
   "source": [
    "import numpy as np\n",
    "print(np.__version__)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "0a0e78ac",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.arange(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1cd07c1d",
   "metadata": {},
   "source": [
    "# Create 3 x 3 numpy array of all True's"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "9389602c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[ True,  True,  True],\n",
       "       [ True,  True,  True],\n",
       "       [ True,  True,  True]])"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.full((3,3),True,dtype=bool)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "69acc192",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[ True,  True,  True],\n",
       "       [ True,  True,  True],\n",
       "       [ True,  True,  True]])"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.ones((3,3),dtype=bool)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7951aceb",
   "metadata": {},
   "source": [
    "# Extract odd number from an array"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "5258de41",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "arr=np.arange(10)\n",
    "arr"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "68746b99",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([1, 3, 5, 7, 9])"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a=arr[arr%2==1]\n",
    "a"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d2acc1bd",
   "metadata": {},
   "source": [
    "# Replace all odd numbers in arr with -1 "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "ec61135d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 0, -1,  2, -1,  4, -1,  6, -1,  8, -1])"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "arr[arr%2==1]=-1\n",
    "arr"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2d22a08f",
   "metadata": {},
   "source": [
    "# Replace all odd numbers in arr with -1 withiout changing "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "a77051d5",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([ 0, -1,  2, -1,  4, -1,  6, -1,  8, -1])"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.where(arr%2==1,-1,arr)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0aaaa72d",
   "metadata": {},
   "source": [
    "# Convert 1D array to a 2D array with 2 rows"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "8eff995a",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.arange(10).reshape(2,5)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "c94162f4",
   "metadata": {},
   "source": [
    "# How to stack arrays a and b vertically"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "29f065a9",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0 1 2 3 4]\n",
      " [5 6 7 8 9]]\n",
      "[[0 1 2 3 4]\n",
      " [5 6 7 8 9]]\n"
     ]
    }
   ],
   "source": [
    "a=np.arange(10).reshape(2,5)\n",
    "b=np.arange(10).reshape(2,5)\n",
    "print(a)\n",
    "print(b)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "ddca7513",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9],\n",
       "       [0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.concatenate((a,b))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "9b1094b7",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9],\n",
       "       [0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.vstack((a,b))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "fdb3e78d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9],\n",
       "       [0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.r_[a,b]"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "33be8c59",
   "metadata": {},
   "source": [
    "# Stack the  arrays a and b horizontally"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "09709fd6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4, 0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9, 5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.hstack((a,b))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "c51c5c12",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4, 0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9, 5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.concatenate((a,b),axis=1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "b0531db6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0, 1, 2, 3, 4, 0, 1, 2, 3, 4],\n",
       "       [5, 6, 7, 8, 9, 5, 6, 7, 8, 9]])"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.c_[a,b]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "id": "27516867",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([1, 2, 3])"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a=np.array([1,2,3])\n",
    "a"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7c805e02",
   "metadata": {},
   "source": [
    "# Create the following pattern without hard coding\n",
    "#array([1, 1, 1, 2, 2, 2, 3, 3, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "9075706c",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([1, 1, 1, 2, 2, 2, 3, 3, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3])"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "np.r_[np.repeat(a,3),np.tile(a,3)]"
   ]
  }
 ],
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