numpy_exercices__solutions.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "r9CJm37Sp1AS"
   },
   "source": [
    "#### 1. Import the numpy package under the name `np` (★☆☆)\n",
    "`hint: import … as`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "id": "BwyUJtfupwP1"
   },
   "outputs": [],
   "source": [
    "import numpy as np\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "363G82K7qFVP"
   },
   "source": [
    "#### 2. Print the numpy version and the configuration (★☆☆)\n",
    "`hint: np.__version__, np.show_config)`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "id": "xp00q7jCqH2f"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1.20.3\n"
     ]
    }
   ],
   "source": [
    "print(np.__version__)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "zn-aZj0YqSDu"
   },
   "source": [
    "#### 3. Create a null vector of size 10 (★☆☆)\n",
    "`hint: np.zeros`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "id": "-p7lt6_WqUpE"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]\n"
     ]
    }
   ],
   "source": [
    "Z = np.zeros(10)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "wTjyJ_btqZSH"
   },
   "source": [
    "\n",
    "#### 4. How to find the memory size of any array (★☆☆)\n",
    "`hint: size, itemsize`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "id": "uFo-zE4jqdPY"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "800 bytes\n"
     ]
    }
   ],
   "source": [
    "Z = np.zeros((10,10))\n",
    "print(\"%d bytes\" % (Z.size * Z.itemsize))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "gLt6m_sKq7Uc"
   },
   "source": [
    "#### 6. Create a null vector of size 10 but the fifth value which is 1 (★☆☆)\n",
    "`hint: array[4]`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "id": "Em_4fUenrGwi"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0. 0. 0. 0. 1. 0. 0. 0. 0. 0.]\n"
     ]
    }
   ],
   "source": [
    "Z = np.zeros(10)\n",
    "Z[4] = 1\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "UqPUjuH9rHb9"
   },
   "source": [
    "#### 7. Create a vector with values ranging from 10 to 49 (★☆☆)\n",
    "`hint: arange`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "id": "T7qWyM0XrP2Z"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33\n",
      " 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49]\n"
     ]
    }
   ],
   "source": [
    "Z = np.arange(10,50)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "M2dcJfidrX79"
   },
   "source": [
    "#### 8. Reverse a vector (first element becomes last) (★☆☆)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "id": "v8w9r3j3riMZ"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26\n",
      " 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2\n",
      "  1  0]\n"
     ]
    }
   ],
   "source": [
    "Z = np.arange(50)\n",
    "Z = Z[::-1]\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "mXfOFXyxrjJq"
   },
   "source": [
    "#### 9. Create a 3x3 matrix with values ranging from 0 to 8 (★☆☆)\n",
    "`hint: reshape`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "id": "vDG3fL98rrn8"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0 1 2]\n",
      " [3 4 5]\n",
      " [6 7 8]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.arange(9).reshape(3, 3)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "yn4QmUxErv-j"
   },
   "source": [
    "#### 10. Find indices of non-zero elements from [1,2,0,0,4,0] (★☆☆)\n",
    "`hint: np.nonzero`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "id": "pK2Pc0vJrzGb"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(array([0, 1, 4], dtype=int64),)\n"
     ]
    }
   ],
   "source": [
    "nz = np.nonzero([1,2,0,0,4,0])\n",
    "print(nz)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "ZQhz7HQBr1j1"
   },
   "source": [
    "#### 11. Create a 3x3 identity matrix (★☆☆)\n",
    "`hint: np.eye`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "id": "AFjcN2DMr-jl"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[1. 0. 0.]\n",
      " [0. 1. 0.]\n",
      " [0. 0. 1.]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.eye(3)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "ZLgZ1j07sMuC"
   },
   "source": [
    "#### 12. Create a 3x3x3 array with random values (★☆☆)\n",
    "`hint: np.random.random`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "id": "vSKc1QY2sQhP"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[[0.47660316 0.46581244 0.07811393]\n",
      "  [0.60468023 0.788748   0.19663203]\n",
      "  [0.80353368 0.47153702 0.3773618 ]]\n",
      "\n",
      " [[0.28797704 0.49886819 0.41352191]\n",
      "  [0.41140956 0.6384109  0.91958613]\n",
      "  [0.56174641 0.81479565 0.18506088]]\n",
      "\n",
      " [[0.43229689 0.90702859 0.01875094]\n",
      "  [0.379409   0.82637047 0.01814941]\n",
      "  [0.59542959 0.78651544 0.63968542]]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.random.random((3,3,3))\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "7bHUxEEpsShj"
   },
   "source": [
    "#### 13. Create a 10x10 array with random values and find the minimum and maximum values (★☆☆)\n",
    "`hint: min, max`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "id": "TIuRYqwusVgJ"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0.008728843372194928 0.9916643358737559\n"
     ]
    }
   ],
   "source": [
    "Z = np.random.random((10,10))\n",
    "Zmin, Zmax = Z.min(), Z.max()\n",
    "print(Zmin, Zmax)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "Ryy8RMjFsZA3"
   },
   "source": [
    "\n",
    "#### 14. Create a random vector of size 30 and find the mean value (★☆☆)\n",
    "`hint: mean`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "id": "89x8qiQssb87"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0.45730627985350597\n"
     ]
    }
   ],
   "source": [
    "Z = np.random.random(30)\n",
    "m = Z.mean()\n",
    "print(m)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "LGGF142tsfxU"
   },
   "source": [
    "#### 15. Create a 2d array with 1 on the border and 0 inside (★☆☆)\n",
    "`hint: array[1:-1, 1:-1]`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "id": "JGnRF3DfsiC6"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 0. 0. 0. 0. 0. 0. 0. 0. 1.]\n",
      " [1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.ones((10,10))\n",
    "Z[1:-1,1:-1] = 0\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "aw7Zx2ShslAT"
   },
   "source": [
    "#### 16. How to add a border (filled with 0's) around an existing array? (★☆☆)\n",
    "`hint: np.pad`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "id": "kDKOthagst-X"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0. 0. 0. 0. 0. 0. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 0. 0. 0. 0. 0. 0.]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.ones((5,5))\n",
    "Z = np.pad(Z, pad_width=1, mode='constant', constant_values=0)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "id": "eSb_9Wcds2iB"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0. 0. 0. 0. 0. 0. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 1. 1. 1. 1. 1. 0.]\n",
      " [0. 0. 0. 0. 0. 0. 0.]]\n"
     ]
    }
   ],
   "source": [
    "# Using fancy indexing\n",
    "Z[:, [0, -1]] = 0\n",
    "Z[[0, -1], :] = 0\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "QQFcOljotDoS"
   },
   "source": [
    "#### 17. What is the result of the following expression? (★☆☆)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "id": "ENOv_i6xtBJN"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "nan\n",
      "False\n",
      "False\n",
      "nan\n",
      "True\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "print(0 * np.nan)\n",
    "print(np.nan == np.nan)\n",
    "print(np.inf > np.nan)\n",
    "print(np.nan - np.nan)\n",
    "print(np.nan in set([np.nan]))\n",
    "print(0.3 == 3 * 0.1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "8OXdu50YtJvR"
   },
   "source": [
    "\n",
    "#### 18. Create a 5x5 matrix with values 1,2,3,4 just below the diagonal (★☆☆)\n",
    "`hint: np.diag`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "id": "eQLjZ7OGtPxD"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0 0 0 0 0]\n",
      " [1 0 0 0 0]\n",
      " [0 2 0 0 0]\n",
      " [0 0 3 0 0]\n",
      " [0 0 0 4 0]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.diag(1+np.arange(4),k=-1)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "tDfFbBl3tT-F"
   },
   "source": [
    "#### 19. Create a 8x8 matrix and fill it with a checkerboard pattern (★☆☆)\n",
    "`hint: array[::2]`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "id": "oFhpWp6Utogv"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0 1 0 1 0 1 0 1]\n",
      " [1 0 1 0 1 0 1 0]\n",
      " [0 1 0 1 0 1 0 1]\n",
      " [1 0 1 0 1 0 1 0]\n",
      " [0 1 0 1 0 1 0 1]\n",
      " [1 0 1 0 1 0 1 0]\n",
      " [0 1 0 1 0 1 0 1]\n",
      " [1 0 1 0 1 0 1 0]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.zeros((8,8),dtype=int)\n",
    "Z[1::2,::2] = 1\n",
    "Z[::2,1::2] = 1\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "5D-xeFztuXO5"
   },
   "source": [
    "#### 20. Consider a (6,7,8) shape array, what is the index (x,y,z) of the 100th element? (★☆☆)\n",
    "`hint: np.unravel_index`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "id": "uYPRC5EquTba"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 5, 3)\n"
     ]
    }
   ],
   "source": [
    "\n",
    "print(np.unravel_index(99,(6,7,8)))\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "GSzKmfIsu3IW"
   },
   "source": [
    "#### 22. Normalize a 5x5 random matrix (★☆☆)\n",
    "`hint: (x -mean)/std`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "id": "wI05FJpVu7Lb"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[ 0.90579414  1.24226322  0.98079371  1.12584087  0.88394775]\n",
      " [ 1.18773203 -1.34569465 -0.83223754 -0.59168495  0.10512106]\n",
      " [-0.30174352 -0.15599349 -1.36160413 -1.25282631  0.59267215]\n",
      " [ 1.26030826 -1.24319852  0.90052292 -1.43225829 -0.62584794]\n",
      " [-0.75631118 -1.17572326  1.13249731  1.25862821 -0.50099785]]\n"
     ]
    }
   ],
   "source": [
    "\n",
    "Z = np.random.random((5,5))\n",
    "Z = (Z - np.mean (Z)) / (np.std (Z))\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "y02XGEFBu_X3"
   },
   "source": [
    "#### 23. Create a custom dtype that describes a color as four unsigned bytes (RGBA) (★☆☆)\n",
    "`hint: np.dtype`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {
    "id": "XA6rGdq8vIZa"
   },
   "outputs": [],
   "source": [
    "color = np.dtype([(\"r\", np.ubyte),\n",
    "                  (\"g\", np.ubyte),\n",
    "                  (\"b\", np.ubyte),\n",
    "                  (\"a\", np.ubyte)])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "rKuhwTF5vMMp"
   },
   "source": [
    "#### 24. Multiply a 5x3 matrix by a 3x2 matrix (real matrix product) (★☆☆)\n",
    "`hint:`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {
    "id": "CikGAR5_vRFw"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[3. 3.]\n",
      " [3. 3.]\n",
      " [3. 3.]\n",
      " [3. 3.]\n",
      " [3. 3.]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.dot(np.ones((5,3)), np.ones((3,2)))\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "FW9Kh3mjvgyQ"
   },
   "source": [
    "#### 25. Given a 1D array, negate all elements which are between 3 and 8, in place. (★☆☆)\n",
    "`hint: >, <`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {
    "id": "CE7CSIhJvjr0"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[ 0  1  2  3 -4 -5 -6 -7  8  9 10]\n"
     ]
    }
   ],
   "source": [
    "\n",
    "Z = np.arange(11)\n",
    "Z[(3 < Z) & (Z < 8)] *= -1\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "-LYPgYGEv2YL"
   },
   "source": [
    "#### 29. How to round away from zero a float array ? (★☆☆)\n",
    "`hint: np.uniform, np.copysign, np.ceil, np.abs, np.where`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {
    "id": "OM7oaOSfv3iY"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[-6.2526292   7.81021594  7.7867736  -8.69119501 -4.57372719  4.57926251\n",
      " -4.3608191  -4.45017704  4.30692487  1.18464846]\n",
      "[-7.  8.  8. -9. -5.  5. -5. -5.  5.  2.]\n"
     ]
    }
   ],
   "source": [
    "Z = np.random.uniform(-10,+10,10)\n",
    "print(Z)\n",
    "print(np.copysign(np.ceil(np.abs(Z)), Z))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "mJDvNUI2wp6z"
   },
   "source": [
    "\n",
    "#### 30. How to find common values between two arrays? (★☆☆)\n",
    "`hint: np.intersect1d`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "id": "NlJr_AaFwv-d"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1 4 5 6]\n"
     ]
    }
   ],
   "source": [
    "Z1 = np.random.randint(0,10,10)\n",
    "Z2 = np.random.randint(0,10,10)\n",
    "print(np.intersect1d(Z1,Z2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "w326fljBw2LZ"
   },
   "source": [
    "#### 31. How to ignore all numpy warnings (not recommended)? (★☆☆)\n",
    "`hint: np.seterr, np.errstate`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {
    "id": "-O0sn8Agw9Yh"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([inf])"
      ]
     },
     "execution_count": 27,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "defaults = np.seterr(all=\"ignore\")\n",
    "Z = np.ones(1) / 0\n",
    "Z"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "fozP_AmtxOEj"
   },
   "source": [
    "\n",
    "#### 33. How to get the dates of yesterday, today and tomorrow? (★☆☆)\n",
    "`hint: np.datetime64, np.timedelta64`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {
    "id": "cNmOfyZFxP6E"
   },
   "outputs": [],
   "source": [
    "yesterday = np.datetime64('today') - np.timedelta64(1)\n",
    "today     = np.datetime64('today')\n",
    "tomorrow  = np.datetime64('today') + np.timedelta64(1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "ZDDI60baxbsB"
   },
   "source": [
    "#### 34. How to get all the dates corresponding to the month of July 2016? (★★☆)\n",
    "`hint: np.arange(dtype=datetime64['D'])`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {
    "id": "tFa48hQfxkWi"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['2016-07-01' '2016-07-02' '2016-07-03' '2016-07-04' '2016-07-05'\n",
      " '2016-07-06' '2016-07-07' '2016-07-08' '2016-07-09' '2016-07-10'\n",
      " '2016-07-11' '2016-07-12' '2016-07-13' '2016-07-14' '2016-07-15'\n",
      " '2016-07-16' '2016-07-17' '2016-07-18' '2016-07-19' '2016-07-20'\n",
      " '2016-07-21' '2016-07-22' '2016-07-23' '2016-07-24' '2016-07-25'\n",
      " '2016-07-26' '2016-07-27' '2016-07-28' '2016-07-29' '2016-07-30'\n",
      " '2016-07-31']\n"
     ]
    }
   ],
   "source": [
    "Z = np.arange('2016-07', '2016-08', dtype='datetime64[D]')\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "vO09xlXbxutT"
   },
   "source": [
    "#### 35. How to compute ((A+B)*(-A/2)) in place (without copy)? (★★☆)\n",
    "`hint: np.add(out=), np.negative(out=), np.multiply(out=), np.divide(out=)`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {
    "id": "5piIc22BxthV"
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([-1.5, -1.5, -1.5])"
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "A = np.ones(3)*1\n",
    "B = np.ones(3)*2\n",
    "np.add(A,B,out=B)\n",
    "np.divide(A,2,out=A)\n",
    "np.negative(A,out=A)\n",
    "np.multiply(A,B,out=A)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "0SBdobj7xzsb"
   },
   "source": [
    "#### 36. Extract the integer part of a random array of positive numbers using 4 different methods (★★☆)\n",
    "\n",
    "```\n",
    "`hint: %, np.floor, astype, np.trunc`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {
    "id": "syC3Xhrvx6Q5"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1. 8. 4. 4. 9. 4. 1. 5. 2. 6.]\n",
      "[1. 8. 4. 4. 9. 4. 1. 5. 2. 6.]\n",
      "[1. 8. 4. 4. 9. 4. 1. 5. 2. 6.]\n",
      "[1 8 4 4 9 4 1 5 2 6]\n",
      "[1. 8. 4. 4. 9. 4. 1. 5. 2. 6.]\n"
     ]
    }
   ],
   "source": [
    "Z = np.random.uniform(0,10,10)\n",
    "\n",
    "print(Z - Z%1)\n",
    "print(Z // 1)\n",
    "print(np.floor(Z))\n",
    "print(Z.astype(int))\n",
    "print(np.trunc(Z))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "GMR3grkex9xq"
   },
   "source": [
    "#### 37. Create a 5x5 matrix with row values ranging from 0 to 4 (★★☆)\n",
    "`hint: np.arange`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {
    "id": "lj0TTvO2x_xy"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[[0. 1. 2. 3. 4.]\n",
      " [0. 1. 2. 3. 4.]\n",
      " [0. 1. 2. 3. 4.]\n",
      " [0. 1. 2. 3. 4.]\n",
      " [0. 1. 2. 3. 4.]]\n"
     ]
    }
   ],
   "source": [
    "Z = np.zeros((5,5))\n",
    "Z += np.arange(5)\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "14OZ-DWfyTZf"
   },
   "source": [
    "\n",
    "\n",
    "#### 39. Create a vector of size 10 with values ranging from 0 to 1, both excluded (★★☆)\n",
    "`hint: np.linspace`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {
    "id": "5YVphcuyyQH1"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0.09090909 0.18181818 0.27272727 0.36363636 0.45454545 0.54545455\n",
      " 0.63636364 0.72727273 0.81818182 0.90909091]\n"
     ]
    }
   ],
   "source": [
    "\n",
    "Z = np.linspace(0,1,11,endpoint=False)[1:]\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "id": "nQdFxvxxyZAv"
   },
   "source": [
    "#### 40. Create a random vector of size 10 and sort it (★★☆)\n",
    "`hint: sort`\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {
    "id": "itx_53pFybTQ"
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[0.00185033 0.22363672 0.38605187 0.45402973 0.66418849 0.68281823\n",
      " 0.80602597 0.84493633 0.86297532 0.9454821 ]\n"
     ]
    }
   ],
   "source": [
    "\n",
    "Z = np.random.random(10)\n",
    "Z.sort()\n",
    "print(Z)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "id": "vJzx84ompuXN"
   },
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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