[Tutor] problem loading and array from an external file

[bob gailer]

On 8/9/2010 11:13 PM, Bill Allen wrote:
> Bob,
>
> Thanks for the feedback.  I have been stepping through it in the IDLE
> debugger.  However, it may be that I am letting the debugger get in my
> way as I am new to it also.  You are right.   I'll get out the old
> yellow legal pad and step through it by hand.  In fact, I think I will
> process the loop entirely by hand, just the logic, and see how the
> variables look that way.
>
>    
Glad I could help.

PLEASE remember to always reply-all so a copy goes to the list.

> Thanks,
> Bill
>
>
> On Mon, Aug 9, 2010 at 10:08 PM, bob gailer<bgailer at gmail.com>  wrote:
>    
>> On 8/9/2010 10:55 PM, Bill Allen wrote:
>>      
>>> Hi, my name is Bill and I am completely stuck.  I have a little bit of
>>> code I am working with for the sole purpose of coding in order to
>>> learn Python.  In order to learn a programming language, I very often
>>> use a little text based map of rooms traversal game.  So far, so good.
>>>   However, this time I decided to learn some file operations so I am
>>> trying to read the data in from an external file rather than
>>> preloading an array inside the code itself.  I am able to open the
>>> file and read from it.  However, I am getting unexpected results when
>>> filling the array.  Instead of each row in the array being loaded with
>>> the matching line in the data file, by the end of the loops all the
>>> rows in the array end up being filled with the last line of the data
>>> file.   I have stepped and traced through it and cannot figure out
>>> where I am going wrong.
>>>        
>> How did you step thru it? If you do it very precisely the problem will be
>> evident.
>> I'd prefer you discover it by careful step-thru rather than feeding you the
>> answer.
>>
>>      
>>> This may not be a Python issue at all, but is
>>> likely me being way off in the weeds on my algorithm.  This is only
>>> the portion of the code for loading the array from the file.  I am
>>> writing this in Python 3.  I believe my problem is somewhere in the
>>> read_maze_data_file() function.
>>>        
>> That is accurate.
>>
>>      
>>> There are lots of unnecessary extra
>>> print statements in this code because I was trying to carefully follow
>>> the state of the variables as the code ran.  If anyone can point out
>>> where I am going wrong, I would really appreciate it.
>>>
>>>        
>> As mentioned above you have a bug in your step-throuogh process. Write down
>> the variables that are affected by each statement and note their new values.
>>      
>>> The code:
>>> #          N S E W U D
>>> room0 = [0,0,0,0,0,0,0]
>>> room1 = [0,0,0,0,0,0,0]     #Pad the first place so that rooms may
>>> room2 = [0,0,0,0,0,0,0]     #be referenced naturally
>>> room3 = [0,0,0,0,0,0,0]
>>> room4 = [0,0,0,0,0,0,0]          #First places will have special purposes
>>> room5 = [0,0,0,0,0,0,0]
>>> room6 = [0,0,0,0,0,0,0]          #initialize the array with zeros
>>> room7 = [0,0,0,0,0,0,0]
>>>
>>> room = [room0,room1,room2,room3,room4,room5,room6,room7]
>>>
>>>
>>> def clearscreen(numlines=100):
>>>     """Clear the console.
>>>     numlines is an optional argument used only as a fall-back.
>>>     """
>>>     import os
>>>     if os.name == "posix":
>>>         # Unix/Linux/MacOS/BSD/etc
>>>         os.system('clear')
>>>     elif os.name in ("nt", "dos", "ce"):
>>>         # DOS/Windows
>>>         os.system('CLS')
>>>     else:
>>>         # Fallback for other operating systems.
>>>         print('\n' * numlines)
>>>     print(os.name)
>>>
>>> def print_map():
>>>     print("+-------------+")
>>>     print('|','MAP:   ','N','S','E','W','U','D','|', sep="", end="")
>>>     for x in range(1,8):
>>>         print()
>>>         print("|","room",x,">    ", sep="", end="")
>>>         for y in range(1,7):
>>>             print(room[x][y], end="")
>>>         print("|", end="")
>>>     print()
>>>     print("+-------------+", end="")
>>>
>>>
>>> def read_maze_data_file():
>>>
>>>     roomx = [0,0,0,0,0,0,0]
>>>     n, m = 0, 0
>>>
>>>     try:
>>>       filename = 'mazegame.dat'
>>>       textf = open(filename, 'r')
>>>     except IOError:
>>>       print ('Cannot open file %s for reading' % filename)
>>>       import sys
>>>       sys.exit(0)
>>>
>>> # reads one line at a time
>>>
>>>     for line in textf:
>>>         print("raw line in file: ",line, end="")
>>>         tempwords = line.split(None)
>>>         print ("line as read from file: ",tempwords)
>>>
>>>         for n in range(0, len(room)-1):
>>>             roomx[n] = tempwords[n]
>>>             #print(roomx[n])
>>>
>>>         print("roomx",roomx)
>>>         room[m] = roomx
>>>         print("room ",m,room[m])
>>>         print("current state of room array")
>>>         print("room 0",room[0])
>>>         print("room 1",room[1])
>>>         print("room 2",room[2])
>>>         print("room 3",room[3])
>>>         print("room 4",room[4])
>>>         print("room 5",room[5])
>>>         print("room 6",room[6])
>>>         print("room 7",room[7])
>>>
>>>         m += 1
>>>
>>>     textf.close()
>>>     return(room)
>>>
>>> #----END read_maze_data_file()
>>>
>>>
>>> #---------MAIN SECTION---------
>>>
>>> clearscreen()
>>>
>>>
>>> print("LOAD AN ARRARY FROM A FILE")
>>> print("              by Bill Allen")
>>> print()
>>> print("initial state of room array")
>>> print(room)
>>> print()
>>>
>>> print("data from file")
>>> room_final = read_maze_data_file()
>>> print("from MAIN")
>>> print(room_final)
>>> print()
>>>
>>> print("a PRINT_MAP call from MAIN")
>>> print_map()
>>> print()
>>> print()
>>>
>>>
>>> =======================
>>> partial sample output showing the current incorrect results:
>>> a PRINT_MAP call from MAIN
>>> +-------------+
>>> |MAP:   NSEWUD|
>>> |room1>    000050|
>>> |room2>    000050|
>>> |room3>    000050|
>>> |room4>    000050|
>>> |room5>    000050|
>>> |room6>    000050|
>>> |room7>    000050|
>>> +-------------+
>>> =========================
>>> the contents of the data file, mazegame.dat
>>> 0 0 0 0 0 0 0
>>> 0 0 4 2 0 0 0
>>> 0 0 0 1 3 6 0
>>> 0 0 5 0 2 0 0
>>> 0 1 0 5 0 0 0
>>> 0 3 0 0 4 0 7
>>> 0 0 0 0 0 0 2
>>> 0 0 0 0 0 5 0
>>> _______________________________________________
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>>>
>>>        
>>
>> --
>> Bob Gailer
>> 919-636-4239
>> Chapel Hill NC
>>
>>
>>      
>    


-- 
Bob Gailer
919-636-4239
Chapel Hill NC