{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In lecture 9 of mcs 320, we save data and load data from file."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 1. Saving Data as Plain Text"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.1415926535897932385 has type <class 'sage.rings.real_mpfr.RealNumber'>\n"
     ]
    }
   ],
   "source": [
    "x = pi.n(digits=20)\n",
    "print(x, 'has type', type(x))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We will write the string representation of x to file."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.1415926535897932385 has type <class 'str'>\n"
     ]
    }
   ],
   "source": [
    "sx = str(x)\n",
    "print(sx, 'has type', type(sx))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "file = open('mydata.txt', 'w')\n",
    "file.write(sx)\n",
    "file.close()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can check what is in the listing of the current directory."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['.ipynb_checkpoints',\n",
       " '.READ_ME.un~',\n",
       " 'mcs320lec09.ipynb',\n",
       " 'mcs320lec09s19.ipynb',\n",
       " 'mydata.txt',\n",
       " 'pickledresult.txt',\n",
       " 'READ_ME',\n",
       " 'READ_ME~',\n",
       " 'sageobject.sobj']"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import os\n",
    "os.listdir('.')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "x"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "reset() # clear everything\n",
    "x"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.1415926535897932385 has type <class 'str'>\n"
     ]
    }
   ],
   "source": [
    "file = open('mydata.txt', 'r')\n",
    "line = file.readline()\n",
    "print(line, 'has type', type(line))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now that we have the string, we have to convert this back into a proper SageMath object.\n",
    "Python question: what is the opposite of ``str()``?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We could cast our number to a float."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3.141592653589793"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "float(line)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3.14159265358979"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "RR(line)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.141592653589793 has type <class 'float'>\n"
     ]
    }
   ],
   "source": [
    "ex = eval(line)\n",
    "print(ex, 'has type', type(ex))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In SageMath, we have to call the preparser on the string, before evaluation."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "RealNumber('3.1415926535897932385') has type <class 'str'>\n"
     ]
    }
   ],
   "source": [
    "px = preparse(line)\n",
    "print(px, 'has type', type(px))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.141592653589793239 has type <class 'sage.rings.real_mpfr.RealLiteral'>\n"
     ]
    }
   ],
   "source": [
    "result = eval(px)\n",
    "print(result, 'has type', type(result))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 2. Saving Objects with save() and Retrieving with load()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.141592653589793239 has type <class 'sage.rings.real_mpfr.RealLiteral'>\n"
     ]
    }
   ],
   "source": [
    "print(result, 'has type', type(result))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "result.save('sageobject')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['.ipynb_checkpoints',\n",
       " '.READ_ME.un~',\n",
       " 'mcs320lec09.ipynb',\n",
       " 'mcs320lec09s19.ipynb',\n",
       " 'mydata.txt',\n",
       " 'pickledresult.txt',\n",
       " 'READ_ME',\n",
       " 'READ_ME~',\n",
       " 'sageobject.sobj']"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.listdir('.')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "result"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# reset('result')\n",
    "# result\n",
    "result = var('result')\n",
    "result"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.141592653589793239 has type <class 'sage.rings.real_mpfr.RealNumber'>\n"
     ]
    }
   ],
   "source": [
    "result = load('sageobject')\n",
    "print(result, 'has type', type(result))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 3. Pickling Python Objects"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "b'\\x80\\x03csage.rings.real_mpfr\\n__create__RealNumber_version0\\nq\\x00csage.rings.real_mpfr\\n__create__RealField_version0\\nq\\x01KC\\x89X\\x04\\x00\\x00\\x00RNDNq\\x02\\x87q\\x03Rq\\x04X\\x12\\x00\\x00\\x003.4gvml245kc4d80@0q\\x05K \\x87q\\x06Rq\\x07.'"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import pickle\n",
    "pr = pickle.dumps(result)\n",
    "pr"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The pickled object contains the type information.\n",
    "We can write this to a file, as a string."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [],
   "source": [
    "file = open('pickledresult.txt', 'w')\n",
    "file.write(str(pr))\n",
    "file.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['.ipynb_checkpoints',\n",
       " '.READ_ME.un~',\n",
       " 'mcs320lec09.ipynb',\n",
       " 'mcs320lec09s19.ipynb',\n",
       " 'mydata.txt',\n",
       " 'pickledresult.txt',\n",
       " 'READ_ME',\n",
       " 'READ_ME~',\n",
       " 'sageobject.sobj']"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "os.listdir('.')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "result"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "result = var('result')\n",
    "result"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "With ``del`` (a pure Python command), we deleted the object result.\n",
    "Unlike the ``result = var('result')`` the name result does not exist.\n",
    "Now we will retrieve the pickled data."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[\"b'\\\\x80\\\\x03csage.rings.real_mpfr\\\\n__create__RealNumber_version0\\\\nq\\\\x00csage.rings.real_mpfr\\\\n__create__RealField_version0\\\\nq\\\\x01KC\\\\x89X\\\\x04\\\\x00\\\\x00\\\\x00RNDNq\\\\x02\\\\x87q\\\\x03Rq\\\\x04X\\\\x12\\\\x00\\\\x00\\\\x003.4gvml245kc4d80@0q\\\\x05K \\\\x87q\\\\x06Rq\\\\x07.'\"] has type <class 'list'>\n"
     ]
    }
   ],
   "source": [
    "file = open('pickledresult.txt', 'r')\n",
    "lines = file.readlines()\n",
    "print(lines, 'has type', type(lines))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Question: how do we turn a list of strings into one big string?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"b'\\\\x80\\\\x03csage.rings.real_mpfr\\\\n__create__RealNumber_version0\\\\nq\\\\x00csage.rings.real_mpfr\\\\n__create__RealField_version0\\\\nq\\\\x01KC\\\\x89X\\\\x04\\\\x00\\\\x00\\\\x00RNDNq\\\\x02\\\\x87q\\\\x03Rq\\\\x04X\\\\x12\\\\x00\\\\x00\\\\x003.4gvml245kc4d80@0q\\\\x05K \\\\x87q\\\\x06Rq\\\\x07.'\""
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "joinedpr = ''.join(lines)\n",
    "joinedpr"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "b'\\x80\\x03csage.rings.real_mpfr\\n__create__RealNumber_version0\\nq\\x00csage.rings.real_mpfr\\n__create__RealField_version0\\nq\\x01KC\\x89X\\x04\\x00\\x00\\x00RNDNq\\x02\\x87q\\x03Rq\\x04X\\x12\\x00\\x00\\x003.4gvml245kc4d80@0q\\x05K \\x87q\\x06Rq\\x07.' has type <class 'bytes'>\n"
     ]
    }
   ],
   "source": [
    "bytejoinedpr = eval(joinedpr)\n",
    "print(bytejoinedpr, 'has type', type(bytejoinedpr))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3.141592653589793239 has type <class 'sage.rings.real_mpfr.RealNumber'>\n"
     ]
    }
   ],
   "source": [
    "r = pickle.loads(bytejoinedpr)\n",
    "print(r, 'has type', type(r))"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "SageMath 10.3",
   "language": "sage",
   "name": "sagemath"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.10"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}