Reading and Writing Files February 25, 2017 1 Reading and Writing - - PDF document

Reading and Writing Files

February 25, 2017

1 Reading and Writing Files in Python

1.0.1 CS 0155 - Data Witchcraft - Spring 2017 1.0.2

• Dr. Alexandros Labrinidis

In [1]: # Encode a 5x5 character as a list of 5 rows letterA = ['..x..','.x.x.','xxxxx','x...x','x...x'] # We expect . to be converted to a space character for row in letterA: # iterate over all rows in the list print (row) ..x.. .x.x. xxxxx x...x x...x In [2]: letterA = ['..x..','.x.x.','xxxxx','x...x','x...x'] for row in letterA: # iterate over all rows in the list for letter in row: # iterate over all characters in the string print (letter,end='') print () ..x.. .x.x. xxxxx x...x x...x In [3]: #letterA = ['..X..','.x.x.','xxxxx','x...x','x...x'] letterA = ['.XXX.','X...X','XXXXX','X...X','X...X'] for row in letterA: 1

# iterate over all rows in the list for letter in row: # iterate over all characters in the string if (letter != '.'): print (letter, end='') else: # print . characters as spaces print (' ', end='') print () XXX X X XXXXX X X X X In [4]: # open file testfile for writing newfile = open('testfile',"w") for row in letterA: # write string row into testfile newfile.write(row) # make sure we switch to next line newfile.write('\n') newfile.close() In [5]: # open file testfile for reading fh = open('testfile','r') lili = fh.readlines() print (lili) for one in lili: print (one, end='') ['.XXX.\n', 'X...X\n', 'XXXXX\n', 'X...X\n', 'X...X\n'] .XXX. X...X XXXXX X...X X...X In [6]: # Recap letterA = ['..x..', '.x.x.', 'xxxxx', 'x...x', 'x...x'] print (letterA) 2

['..x..', '.x.x.', 'xxxxx', 'x...x', 'x...x'] In [7]: # Store letters in a dictionary all_letters = { 'a': ['..x..', '.x.x.', 'xxxxx', 'x...x', 'x...x']} In [8]: # READ IN all letters AND store in dictionary data structure # assume these are available in the current directory myletters = {} for letter in "abcdefghijklmnopqrstuvwxyz": #print ('LETTER',letter) filename = 'incoming/'+letter+'.txt' print ('FILENAME',filename) fh = open(filename,'r') myletters[letter] = fh.readlines() print (myletters[letter]) fh.close() print (myletters) FILENAME incoming/a.txt ['..x..\n', 'x...x\n', 'xxxxx\n', 'x...x\n', 'x...x\n', '\n'] FILENAME incoming/b.txt ['x...\n', 'x...\n', 'xxx..\n', 'x.x..\n', 'xx...\n'] FILENAME incoming/c.txt ['xxxx.\n', 'x...\n', 'x...\n', 'x...\n', 'xxxx.'] FILENAME incoming/d.txt ['****.\n', '*...*\n', '*...*\n', '*...*\n', '****. '] FILENAME incoming/e.txt ['****.\n', '*... \n', '****.\n', '*... \n', '****.\n'] FILENAME incoming/f.txt ['****.\n', '*...\n', '****.\n', '*... \n', '*... \n'] FILENAME incoming/g.txt ['xxxxx\n', 'x...\n', 'x.xxx\n', 'x...x\n', 'xxxxx'] FILENAME incoming/h.txt ['X...X\n', 'X...X\n', 'XXXXX\n', 'X...X\n', 'X...X\n'] FILENAME incoming/i.txt ['XXXXX\n', '..X..\n', '..X..\n', '..X..\n', 'XXXXX'] FILENAME incoming/j.txt ['..XXX\n', '...X.\n', '...X.\n', 'X..X.\n', '.XX..'] FILENAME incoming/k.txt ['X..X.\n', 'X.X..\n', 'XX...\n', 'X.X..\n', 'X..X.'] FILENAME incoming/l.txt ['X...\n', 'X...\n', 'X...\n', 'X...\n', 'XXXXX'] FILENAME incoming/m.txt ['.x.x.\n', 'x.x.x\n', 'x.x.x\n', 'x.x.x\n', 'x...x\n'] FILENAME incoming/n.txt ['x...x\n', 'xx..x\n', 'x.x.x\n', 'x..xx\n', 'x...x'] FILENAME incoming/o.txt 3

['.xxx.\n', 'x...x\n', 'x...x\n', 'x...x\n', '.xxx.'] FILENAME incoming/p.txt ['.xxx.\n', '.x.x.\n', '.xxx.\n', '.x...\n', '.x...'] FILENAME incoming/q.txt ['***..\n', '*.*..\n', '***..\n', '..*..\n', '..**. \n'] FILENAME incoming/r.txt ['***..\n', '*..*.\n', '*..*.\n', '***..\n', '*..*.\n'] FILENAME incoming/s.txt ['xxxxx\n', 'x...\n', 'xxxxx\n', '...x\n', 'xxxxx'] FILENAME incoming/t.txt ['xxxxx\n', '..x..\n', '..x..\n', '..x..\n', '..x..'] FILENAME incoming/u.txt ['...\n', 'x...x\n', 'x...x\n', 'x...x\n', 'xxxxx\n'] FILENAME incoming/v.txt ['x...x\n', 'x...x\n', '.x.x.\n', '.x.x.\n', '..x..'] FILENAME incoming/w.txt ['x...x\n', 'x...x\n', 'x.x.x\n', 'x.x.x\n', '..x..'] FILENAME incoming/x.txt ['x...x\n', '.x.x.\n', '..x..\n', '.x.x.\n', 'x...x'] FILENAME incoming/y.txt ['X...X\n', '.X.X.\n', '..X..\n', '..X..\n', '..X..'] FILENAME incoming/z.txt ['XXXXX\n', '...X.\n', '..X..\n', '.X...\n', 'XXXXX'] {'a': ['..x..\n', 'x...x\n', 'xxxxx\n', 'x...x\n', 'x...x\n', '\n'], 'b': ['x...\n', In [9]: # same as before, but now eliminate \n myletters = {} for letter in "abcdefghijklmnopqrstuvwxyz": #print ('LETTER',letter) filename = 'incoming/'+letter+'.txt' print ('FILENAME',filename) fh = open(filename,'r') lili = fh.readlines() #print (lili) myletters[letter] = [] for onestring in lili: #http://stackoverflow.com/questions/275018/how-can-i-remove-chomp-a-newline-in-python newstring = onestring.rstrip() #print (newstring, end='___ ') if (newstring): myletters[letter].append(newstring) print (myletters[letter]) fh.close() print (myletters) FILENAME incoming/a.txt ['..x..', 'x...x', 'xxxxx', 'x...x', 'x...x'] 4

FILENAME incoming/b.txt ['x...', 'x...', 'xxx..', 'x.x..', 'xx...'] FILENAME incoming/c.txt ['xxxx.', 'x...', 'x...', 'x...', 'xxxx.'] FILENAME incoming/d.txt ['****.', '*...*', '*...*', '*...*', '****.'] FILENAME incoming/e.txt ['****.', '*...', '****.', '*...', '****.'] FILENAME incoming/f.txt ['****.', '*...', '****.', '*...', '*...'] FILENAME incoming/g.txt ['xxxxx', 'x...', 'x.xxx', 'x...x', 'xxxxx'] FILENAME incoming/h.txt ['X...X', 'X...X', 'XXXXX', 'X...X', 'X...X'] FILENAME incoming/i.txt ['XXXXX', '..X..', '..X..', '..X..', 'XXXXX'] FILENAME incoming/j.txt ['..XXX', '...X.', '...X.', 'X..X.', '.XX..'] FILENAME incoming/k.txt ['X..X.', 'X.X..', 'XX...', 'X.X..', 'X..X.'] FILENAME incoming/l.txt ['X...', 'X...', 'X...', 'X...', 'XXXXX'] FILENAME incoming/m.txt ['.x.x.', 'x.x.x', 'x.x.x', 'x.x.x', 'x...x'] FILENAME incoming/n.txt ['x...x', 'xx..x', 'x.x.x', 'x..xx', 'x...x'] FILENAME incoming/o.txt ['.xxx.', 'x...x', 'x...x', 'x...x', '.xxx.'] FILENAME incoming/p.txt ['.xxx.', '.x.x.', '.xxx.', '.x...', '.x...'] FILENAME incoming/q.txt ['***..', '*.*..', '***..', '..*..', '..**.'] FILENAME incoming/r.txt ['***..', '*..*.', '*..*.', '***..', '*..*.'] FILENAME incoming/s.txt ['xxxxx', 'x...', 'xxxxx', '...x', 'xxxxx'] FILENAME incoming/t.txt ['xxxxx', '..x..', '..x..', '..x..', '..x..'] FILENAME incoming/u.txt ['...', 'x...x', 'x...x', 'x...x', 'xxxxx'] FILENAME incoming/v.txt ['x...x', 'x...x', '.x.x.', '.x.x.', '..x..'] FILENAME incoming/w.txt ['x...x', 'x...x', 'x.x.x', 'x.x.x', '..x..'] FILENAME incoming/x.txt ['x...x', '.x.x.', '..x..', '.x.x.', 'x...x'] FILENAME incoming/y.txt ['X...X', '.X.X.', '..X..', '..X..', '..X..'] 5

FILENAME incoming/z.txt ['XXXXX', '...X.', '..X..', '.X...', 'XXXXX'] {'a': ['..x..', 'x...x', 'xxxxx', 'x...x', 'x...x'], 'b': ['x...', 'x...', 'xxx..', In [10]: print (myletters['c']) ['xxxx.', 'x...', 'x...', 'x...', 'xxxx.'] In [11]: print (myletters['F'.lower()]) ['****.', '*...', '****.', '*...', '*...'] In [12]: print (myletters['f'.lower()]) ['****.', '*...', '****.', '*...', '*...'] In [13]: print (myletters['='.lower()]) # This breaks -- showcases what happens when key is not in dictionary

• KeyError

Traceback (most recent call last) <ipython-input-13-0ccaf12f4fa6> in <module>()

• ---> 1 print (myletters['='.lower()])

2 # This breaks -- showcases what happens when key is not in dictionary KeyError: '=' In [14]: #specify a default value for when the character is unknown asterisk = ['*****','*...*','*.*.*','*...*','*****'] # get_pattern function definition def get_pattern(aletter): # convert all important characters into lower-case # http://stackoverflow.com/questions/1602934/check-if-a-given-key-already-exists-in-a-dictionary if aletter.lower() in myletters.keys(): return myletters[aletter.lower()] else: return asterisk In [15]: print (get_pattern('f')) 6

['****.', '*...', '****.', '*...', '*...'] In [16]: print (get_pattern('F')) ['****.', '*...', '****.', '*...', '*...'] In [17]: print (get_pattern('bob')) # guaranteed to fail ['*****', '*...*', '*.*.*', '*...*', '*****'] In [18]: # FUNCTION to print only one letter at a time (all rows) def print_one (aletter): for row in get_pattern(aletter): for one in row: if (one != '.'): print ('x', end='') else: print (' ', end='') print () In [19]: print_one('x') x x x x x x x x x In [20]: print_one('v') x x x x x x x x x In [21]: print_one('V') x x x x x x x x x 7

In [22]: print_one('@') xxxxx x x x x x x x xxxxx In [23]: # FUNCTION to print entire word def print_word(myword,cnt): for oneline in range(1,6): for i in range(cnt): for oneletter in myword: print_one_line(oneletter,oneline,cnt) print() In [24]: print (get_pattern('a')) print (get_pattern('a')[1]) ['..x..', 'x...x', 'xxxxx', 'x...x', 'x...x'] x...x In [25]: # function ro print one line at a time. def print_one_line(aletter, aline, cnt): #print ('aletter='+aletter+' / aline='+str(aline)) row = get_pattern(aletter)[aline-1] #print ('row='+row) for one in row: if (one != '.'): # if not a . then print an x print ('x'*cnt, end='') else: # if dot is used, we should print space instead print (' '*cnt, end='') print (' ',end='') In [26]: print_one_line('a',1,2) xx In [27]: print_word('c',1) xxxx x x x xxxx 8

In [28]: print_word('cat',1) xxxx x xxxxx x x x x x xxxxx x x x x x xxxx x x x In [29]: print_word('cat',2) xxxxxxxx xx xxxxxxxxxx xxxxxxxx xx xxxxxxxxxx xx xx xx xx xx xx xx xx xx xxxxxxxxxx xx xx xxxxxxxxxx xx xx xx xx xx xx xx xx xx xxxxxxxx xx xx xx xxxxxxxx xx xx xx In [30]: print_word('cat',3) xxxxxxxxxxxx xxx xxxxxxxxxxxxxxx xxxxxxxxxxxx xxx xxxxxxxxxxxxxxx xxxxxxxxxxxx xxx xxxxxxxxxxxxxxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxxxxxxxxxxxxxx xxx xxx xxxxxxxxxxxxxxx xxx xxx xxxxxxxxxxxxxxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxxxxxxxxxxx xxx xxx xxx xxxxxxxxxxxx xxx xxx xxx xxxxxxxxxxxx xxx xxx xxx In [31]: print_word('alex',4) xxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx 9

xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxx xxxx xxxx xxxx xxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxx xxxx In [32]: print_word('pitt',5) xxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxx xxxxx In [ ]: 10