diagonal list from a matrix

diag.ipynb

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    "l1 = [[1,  2,  3 ],\n",
    "      [5,  7,  13],\n",
    "      [17, 19, 23]]\n",
    "\n",
    "l2 = [[1,  2,  3 ],\n",
    "      [5,  7,  13],\n",
    "      [17, 19, 23],\n",
    "      [29, 31]]\n",
    "\n",
    "l3 = [[1,  2,  3 ],\n",
    "      [5,  7,  13],\n",
    "      [17, 19, 23],\n",
    "      [29, 31, 37]]"
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    "## diag\n",
    "\n",
    "**Arguements:**\n",
    "* matrix: A 2 dimentional list\n",
    "\n",
    "**return:** Boolean of if the number of rows and columns are equal\n",
    "\n",
    "**Expected output:**\n",
    "\n",
    "```\n",
    "l1: (3, 3)\n",
    "Rows are not a uniform lenth\n",
    "l3: (4, 3)\n",
    "```"
   ]
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   "cell_type": "code",
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     "text": [
      "l1: (3, 3)\n",
      "Rows are not a uniform lenth\n",
      "l3: (4, 3)\n"
     ]
    }
   ],
   "source": [
    "def shape(matrix):\n",
    "    if len(row_lens := set([len(l) for l in matrix])) > 1:\n",
    "        raise ValueError(\"Rows are not a uniform lenth\")\n",
    "    return len(matrix), row_lens.pop()\n",
    "    \n",
    "print(f'l1: {shape(l1)}')\n",
    "\n",
    "try:\n",
    "    print(f'l2: {shape(l2)}')\n",
    "except ValueError as e:\n",
    "    print(e)\n",
    "\n",
    "print(f'l3: {shape(l3)}')\n"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## diag\n",
    "\n",
    "**Arguements:**\n",
    "* matrix: A square 2 dimentional list\n",
    "\n",
    "**return:** list of matrix\\[0\\]\\[0\\] through matrix\\[n\\]\\[n\\]\n",
    "\n",
    "**Expected output:**\n",
    "\n",
    "```\n",
    "l1: [1, 7, 23]\n",
    "l1 reversed: [17, 7, 3]\n",
    "l2: ValueError Rows are not a uniform lenth\n",
    "l3: ValueError Matrix is now a square.\n",
    "```"
   ]
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   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "l1: [1, 7, 23]\n",
      "l1 reversed: [17, 7, 3]\n",
      "l2: ValueError Rows are not a uniform lenth\n",
      "l3: ValueError Matrix is now a square.\n"
     ]
    }
   ],
   "source": [
    "def diag(matrix):\n",
    "    if (matrix_shape := shape(matrix))[0] != matrix_shape[1]:\n",
    "        raise ValueError(\"Matrix is now a square.\")\n",
    "\n",
    "    return [row[index] for index, row in enumerate(matrix)]\n",
    "\n",
    "print(f'l1: {diag(l1)}')\n",
    "print(f'l1 reversed: {diag(l1[::-1])}')\n",
    "\n",
    "try:\n",
    "    print(f'l2: {diag(l2)}')\n",
    "except ValueError as e:\n",
    "    print(f'l2: ValueError {e}')\n",
    "\n",
    "try:\n",
    "    print(f'l3: {diag(l3)}')\n",
    "except ValueError as e:\n",
    "    print(f'l3: ValueError {e}')\n"
   ]
  }
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