{
"metadata": {
"name": "",
"signature": "sha256:792ce9bacf230895f9bb69020ed0a90ab017f7ded1cf3c8298370c217c100f66"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 12: Working with Files"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.1, page no. 498"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"import sys\n",
"\n",
"\n",
"mystr = []\n",
"\n",
"print \"Enter an interesting string of up to 80 characters: \",\n",
"mystr = raw_input()\n",
"\n",
"try:\n",
" fp = open(\"myfile.txt\", \"w\")\n",
"except:\n",
" print \"error opening the file...\"\n",
" sys.exit()\n",
"\n",
"for i in range(len(mystr)-1, -1, -1):\n",
" fp.write(mystr[i])\n",
"\n",
"fp.close()\n",
"\n",
"try:\n",
" fp = open(\"myfile.txt\", \"r\")\n",
"except:\n",
" print \"error opening the file...\"\n",
"\n",
"print \"the data read from the file is: \"\n",
"while(True):\n",
" c = fp.read(1)\n",
" if not c:\n",
" break\n",
" print c,\n",
"fp.close()"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter an interesting string of up to 80 characters: "
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Too many cooks spoil the broth.\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
" the data read from the file is: \n",
". h t o r b e h t l i o p s s k o o c y n a m o o T\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.2, page no. 502"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"proverbs = [\"Many a mickle makes a muckle.\\n\",\n",
" \"Too many cooks spoil the broth.\\n\",\n",
" \"He who laughs last didn't get the joke in the first place.\\n\"]\n",
" \n",
"more = []\n",
"\n",
"try:\n",
" fp = open(\"myfile.txt\", \"w\") \n",
"except:\n",
" print \"error opening the file...\"\n",
"for proverb in proverbs:\n",
" fp.write(proverb)\n",
"fp.close()\n",
" \n",
"fp = open(\"myfile.txt\", \"a\")\n",
" \n",
"print \"Enter proverbs of up to 80 characters (separated by '.') or press Enter to end:\\n\",\n",
"string = raw_input().split('.')\n",
"\n",
"\n",
"for str in string:\n",
" fp.write(str+\"\\n\")\n",
"fp.close()\n",
"\n",
"fp = open(\"myfile.txt\", \"r\")\n",
"print \"The proverbs in the file are: \\n\"\n",
"while(True):\n",
" line = fp.readline()\n",
" if not line:\n",
" break\n",
" print line\n",
"fp.close()"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter proverbs of up to 80 characters (separated by '.') or press Enter to end:\n"
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"Every dog has his day. Least said, soonest mended. A stitch in time saves nine. Waste not, want not.\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The proverbs in the file are: \n",
"\n",
"Many a mickle makes a muckle.\n",
"\n",
"Too many cooks spoil the broth.\n",
"\n",
"He who laughs last didn't get the joke in the first place.\n",
"\n",
"Every dog has his day\n",
"\n",
" Least said, soonest mended\n",
"\n",
" A stitch in time saves nine\n",
"\n",
" Waste not, want not\n",
"\n",
"\n",
"\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.3, page no. 507"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"import sys\n",
"\n",
"num1 = 234567\n",
"num2 = 345123\n",
"num3 = 789234\n",
"\n",
"ival = []\n",
"\n",
"try:\n",
" fp = open(\"myfile.txt\", \"w\")\n",
"except:\n",
" print \"Error opening file for writing. Program terminated.\\n\"\n",
" sys.exit()\n",
"\n",
"fp.write(\"%6d %6d %6d\" %(num1, num2, num3))\n",
"fp.close()\n",
"print \"%6ld %6ld %6ld\" %(num1, num2, num3)\n",
"\n",
"try: \n",
" fp = open(\"myfile.txt\", \"r\")\n",
"except:\n",
" print \"Error opening file for reading. Program terminated.\\n\"\n",
" sys.exit()\n",
"\n",
"line = fp.readline()\n",
"line_split = line.split(\" \")\n",
"num4 = int(line_split[0])\n",
"num5 = int(line_split[1])\n",
"num6 = int(line_split[2])\n",
"print \"%6ld %6ld %6ld \" %(num4, num5, num6)\n",
"fp.close\n",
"\n",
"fp = open(\"myfile.txt\", \"r\")\n",
"line = fp.readline()\n",
"line_join = \"\".join(line_split)\n",
"ival.append(int(line_join[0:2]))\n",
"ival.append(int(line_join[2:5]))\n",
"ival.append(int(line_join[5:8]))\n",
"ival.append(int(line_join[8:11]))\n",
"ival.append(int(line_join[11:13]))\n",
"ival.append(int(line_join[13:15]))\n",
"fnum = (float(line_join[15:]))\n",
"\n",
"for i in range(len(ival)):\n",
" print \"%sival[%d] = %d\" %((\"\\n\\t\" if i == 4 else \"\\t\"), i, ival[i]),\n",
"print \"\\nfnum = %f \" %fnum"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"234567 345123 789234\n",
"234567 345123 789234 \n",
"\tival[0] = 23 \tival[1] = 456 \tival[2] = 734 \tival[3] = 512 \n",
"\tival[4] = 37 \tival[5] = 89 \n",
"fnum = 234.000000 \n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.4, page no. 514"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"\n",
"\n",
"import math\n",
"import sys\n",
"\n",
"MEM_PRIMES = 10\n",
"PER_LINE = 8\n",
"filename = \"myfile.bin\"\n",
"fp = None\n",
"primes = [2, 3, 5]\n",
"count = 3\n",
"\n",
"def check(buff, count, n):\n",
" root_N = (1.0 + math.sqrt(n))\n",
" for i in range(0, count):\n",
" if(n % buff[i] == 0):\n",
" return 0\n",
" if(buff[i] > root_N):\n",
" return 1\n",
" return -1\n",
"\n",
"def list_array():\n",
" global primes\n",
" global count\n",
" for j in range(count):\n",
" print \"%10lu\" %primes[j]\n",
" if(((j + 1) % PER_LINE) == 0):\n",
" print \"\\n\"\n",
" \n",
"def list_primes():\n",
" global fp\n",
" global filename\n",
" global count\n",
" global primes\n",
" if(fp):\n",
" try:\n",
" fp = open(filename, \"rb\")\n",
" except:\n",
" print \"Unable to open %s to read primes for output \" %filename\n",
" sys,exit()\n",
" while(True):\n",
" line = fp.readline()\n",
" if line:\n",
" list_array()\n",
" print \"\\n\"\n",
" fp.close()\n",
" else:\n",
" list_array()\n",
"\n",
"def write_file():\n",
" global fp\n",
" global filename\n",
" global count\n",
" global primes\n",
" try:\n",
" fp = open(filename, \"ab\")\n",
" except:\n",
" print \"Unable to open %s to append\\n\" %filename\n",
" sys.exit()\n",
" for prime in primes:\n",
" fp.write(prime+\" \")\n",
" fp.close\n",
" count = 0\n",
"\n",
"def is_prime(n):\n",
" global filename\n",
" global fp\n",
" global primes\n",
" global count \n",
" buff = []\n",
" count = 0\n",
" k = 0\n",
" if(fp):\n",
" try:\n",
" fp = open(filename, \"rb\")\n",
" except:\n",
" print \"Unable to open %s to read. \" %g.filename\n",
" sys.exit()\n",
" while(True):\n",
" line = fp.readline()\n",
" if line:\n",
" nums = line.split(\" \")\n",
" for num in nums:\n",
" buff.append(int(num))\n",
" k = check(buff, count, n)\n",
" if(k == 1):\n",
" fp.close()\n",
" return True\n",
" else: \n",
" break\n",
" fp.close()\n",
" return 1 == check(primes, count, n)\n",
"\n",
"trial = primes[count - 1]\n",
"num_primes = 3\n",
"\n",
"print \"How many primes would you like? \",\n",
"total = int(raw_input())\n",
"total = 4 if total < 4 else total\n",
"print total\n",
"while(num_primes < total):\n",
" trial += 2\n",
" if(is_prime(trial)):\n",
" primes.append(trial)\n",
" count += 1\n",
" num_primes += 1\n",
" if(count == MEM_PRIMES):\n",
" write_file()\n",
"\n",
"if(fp and count > 0):\n",
" write_file()\n",
"list_primes()"
],
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.5, page no. 523"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"class Date:\n",
" day = 0\n",
" month = 0\n",
" year = 0\n",
" \n",
"class Family:\n",
" dob = Date()\n",
" name = \"\"\n",
" pa_name = \"\"\n",
" ma_name = \"\"\n",
"\n",
"members = []\n",
"\n",
"def get_person():\n",
" while(True):\n",
" temp = Family()\n",
" print \"Enter the name of the person: \",\n",
" temp.name = raw_input()\n",
" print \"Enter %s's date of birth (day month year): \" %temp.name\n",
" temp.dob.day = int(raw_input(\"Day: \"))\n",
" temp.dob.month = int(raw_input(\"Month: \"))\n",
" temp.dob.year = int(raw_input(\"Year: \"))\n",
" print \"Who is %s's father? \" %temp.name,\n",
" temp.pa_name = raw_input()\n",
" print \"Who is %s's mother? \" %temp.name,\n",
" temp.ma_name = raw_input()\n",
" print \"\\nDo you want to enter details of a person (Y or N)? \",\n",
" more = raw_input()\n",
" members.append(temp)\n",
" if(more.lower() == 'n'):\n",
" return\n",
"\n",
"def show_person_data():\n",
" fp = open(\"myfile.bin\", \"rb\")\n",
" count = 0\n",
" while(True):\n",
" line = fp.readline()\n",
" if line:\n",
" member_data = line.split(\",\")\n",
" print \"%s's father is %s, and mother is %s.\" %(member_data[0],member_data[4], member_data[5])\n",
" found_relative, relative_info = get_parent_dob(members[count])\n",
" if found_relative:\n",
" print relative_info\n",
" else:\n",
" print \"No info on parents available\"\n",
" else:\n",
" break\n",
" fp.close()\n",
"\n",
"def get_parent_dob(member):\n",
" parent_info = \"\"\n",
" found_relative = False\n",
" for parent in members:\n",
" if parent.name == member.pa_name:\n",
" parent_info = parent_info+\"Pa was born on %d %d %d\" %(parent.dob.day, parent.dob.month, parent.dob.year)\n",
" found_relative = True\n",
" elif parent.name == member.ma_name:\n",
" parent_info = parent_info+\" Ma was born on %d %d %d\" %(parent.dob.day, parent.dob.month, parent.dob.year)\n",
" found_relative = True\n",
" return found_relative, parent_info\n",
"\n",
"\n",
"print \"Do you want to add details of a person ? (Y/N): \",\n",
"more = raw_input()\n",
"if more.lower() == 'n':\n",
" import sys\n",
" sys.exit()\n",
"\n",
"get_person()\n",
"fp = open(\"myfile.bin\", \"wb\")\n",
"for member in members:\n",
" line = member.name+\",\"+str(member.dob.day)+\",\"+str(member.dob.month)+\",\"+str(member.dob.year) +\",\"+member.pa_name+\",\"+member.ma_name\n",
" fp.write(line)\n",
" fp.write(\",\\n\")\n",
"fp.close()\n",
"show_person_data()"
],
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.6, page no. 531"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"MAXLEN = 50\n",
"\n",
"def listfile():\n",
" fp = open(\"mypeople.bin\", \"rb\")\n",
" print \"The folks recorded in the mypeople.bin file are: \"\n",
" while(True):\n",
" line = fp.readline()\n",
" if line:\n",
" print line.split(\",\")[0], \"\\t\\t\\t\\t\\t\", line.split(\",\")[1]\n",
" else:\n",
" break\n",
" fp.close()\n",
"\n",
"answer = 'y'\n",
"fp = open(\"mypeople.bin\", \"wb\")\n",
"while(answer.lower() == 'y'):\n",
" print \"Enter a name less than %d characters: \" %MAXLEN,\n",
" name = raw_input()\n",
" print \"Enter the age of %s: \" %name,\n",
" age = int(raw_input())\n",
" length = len(name)\n",
" line = name+\",\"+str(age)\n",
" fp.write(line)\n",
" fp.write(\" \\n\")\n",
" print \"Do you want to enter another(y or n)? \",\n",
" answer = raw_input()\n",
"fp.close()\n",
"listfile()"
],
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.7, page no. 545"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"class Record:\n",
" name = \"\"\n",
" age = 0\n",
"\n",
"records = []\n",
"\n",
"def write_file(mode):\n",
" global filename\n",
" fp = open(filename, mode)\n",
" more = 'y'\n",
" while(more == 'y'):\n",
" print \"Enter name less than 30 characters: \",\n",
" name = raw_input()\n",
" name = \"%30s\" %name\n",
" print \"Enter age of \", name\n",
" age = raw_input()\n",
" age = \"%3s\" %age\n",
" line = name+\",\"+age\n",
" fp.write(line)\n",
" fp.write(\" \\n\")\n",
" print \"Do you want to enter another (y/n)? \",\n",
" more = raw_input()\n",
" fp.close()\n",
" return\n",
"\n",
"def list_file():\n",
" global filename\n",
" fp = open(filename, \"rb\")\n",
" print \"The folks recorded in the mypeople.bin file are: \"\n",
" while(True):\n",
" line = fp.readline()\n",
" if line:\n",
" line_split = line.split(\",\")\n",
" print line_split[0].strip(), \"\\t\\t\\t\\t\\t\", line_split[1]\n",
" else:\n",
" break\n",
" fp.close()\n",
"\n",
"def remove(fname):\n",
" import os\n",
" os.remove(fname)\n",
"\n",
"def update_file():\n",
" global filename\n",
" new_record = Record()\n",
" fp = open(filename, \"rb+\")\n",
" print \"Enter name to be updated: \",\n",
" update_name = raw_input()\n",
" update_name = \"%30s\"%update_name\n",
" while(True):\n",
" old_pos = fp.tell()\n",
" old_line = fp.readline()\n",
" if old_line:\n",
" if old_line.split(\",\")[0] == update_name:\n",
" print \"You can now enter new name and age for \", update_name\n",
" print \"Enter name less than 30 charactesrs: \",\n",
" new_name = raw_input()\n",
" new_name = \"%30s\"%new_name\n",
" print \"Enter age for \", new_name\n",
" new_age = raw_input()\n",
" new_age = \"%3s\"%new_age\n",
" pos = fp.tell()\n",
" fp.seek(old_pos)\n",
" new_line = new_name+\",\"+new_age+\" \\n\"\n",
" new_line = old_line.replace(old_line, new_line)\n",
" fp.write(new_line)\n",
" else:\n",
" break\n",
" fp.close()\n",
" \n",
"filename = \"my-people.bin\"\n",
"answer = 'q'\n",
"while(True):\n",
" print \"Choose from the following options: \"\n",
" print \"To list the file contents enter L\"\n",
" print \"To create a new file enter C \"\n",
" print \"To add new records enter A\"\n",
" print \"To update existing records enter U\"\n",
" print \"To delete the file enter D\"\n",
" print \"To end the program enter Q: \",\n",
" answer = raw_input()\n",
" if answer.upper() == 'L':\n",
" list_file()\n",
" elif answer.upper() == 'C':\n",
" write_file(\"wb+\")\n",
" print \"File creation complete.\"\n",
" elif answer.upper() == 'A':\n",
" write_file(\"ab+\");\n",
" print \"File append complete.\"\n",
" elif answer.upper() == 'U':\n",
" update_file()\n",
" elif answer.upper() == 'D':\n",
" print \"Are you sure you want to delete %s (y or n)? \",\n",
" confirm_delete = raw_input()\n",
" if(confirm_delete.lower() == 'y'):\n",
" remove(filename)\n",
" elif answer.upper() == 'Q':\n",
" print \"Ending the program. \"\n",
" import sys\n",
" sys.exit()\n",
" else:\n",
" print \"Invalid selection. Try again.\""
],
"language": "python",
"metadata": {},
"outputs": [],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Program 12.8, page no. 551"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import binascii\n",
"\n",
"print \"Enter filename: \",\n",
"filename = raw_input()\n",
"\n",
"f = open(filename, \"r\")\n",
"\n",
"for line in f.readlines():\n",
" print (binascii.hexlify(line)),\n",
" print \" | \", line\n",
"\n",
"f.close()"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter filename: "
]
},
{
"name": "stdout",
"output_type": "stream",
"stream": "stdout",
"text": [
"myfile.txt\n"
]
},
{
"output_type": "stream",
"stream": "stdout",
"text": [
" 2e68746f726220656874206c696f707320736b6f6f6320796e616d206f6f54 | .htorb eht liops skooc ynam ooT\n"
]
}
],
"prompt_number": 14
}
],
"metadata": {}
}
]
}