String Conversion

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January 5th, 2004, 02:55 AM

evod510

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String Conversion

Greetings,

I need some help from any master out there,

I need to convert a string of text from a files into a format that i can understand. Here is the coding that i did:

Code:

blocksize = 88

origfile = open('source.DAT', 'rb')
newfile = open('targer.TXT', 'wb')

while 1:
	datachunk = origfile.read(blocksize)
	if not datachunk:
		newfile.write('end')
		break
	rcd = datachunk[0:1] + ';'
	no = datachunk[1:10] + ';'
	type = datachunk[10:16] + ';'
	date = datachunk[16:28] + ';'
	ref = datachunk[28:40] + ';'
	code = datachunk[40:52] + ';'
	qty = datachunk[52:64] + ';'
	tran1 = datachunk[64:76] + ';'
	tran2 = datachunk[76:88] + ';'

	newfile.write(rcd)
	newfile.write(no)
	newfile.write(type)
	newfile.write(date)
	newfile.write(ref)
	newfile.write(code)
	newfile.write(qty)
	newfile.write(tran1)
	newfile.write(tran2)
	

	newfile.write('\r\n')
origfile.close()
newfile.close()

Now i need to convert the list of code into a list of name
example
if code == 1234 then write apple
if code == 3456 then write orange
etc (more than 50 items)

can anyone guide me how to insert the coding
thanks

January 5th, 2004, 07:54 AM

ragabash

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Re: String Conversion

Quote:

Originally posted by evod510

Now i need to convert the list of code into a list of name
example
if code == 1234 then write apple
if code == 3456 then write orange
etc (more than 50 items)

can anyone guide me how to insert the coding
thanks

Make a dictionary:

codeLookUp = {'1234': 'Apple', '5678':'Orange'}
newfile.write(codeLookUp[code])

-rag

January 5th, 2004, 06:44 PM

evod510

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thanks, I will try it asap.

January 5th, 2004, 11:55 PM

evod510

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Dear ragabash,

something wrong with the coding i think

here is the error message

Code:

newfile.write(codeLookUp[code])
KeyError: 1635

help please

January 6th, 2004, 02:12 AM

netytan

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You need to set up your dictionary (with keys) before hand or you'll end up with a KeyError, so your dictionary doesn't have a key 1635...

Code:

>>> codes = {'1': 'one', '2': 'two', '3': 'three'}
>>> codes
{'1': 'one', '3': 'three', '2': 'two'}
>>> for key, value in codes.items():
	print '%s => %s' % (key, value)

	
1 => one
3 => three
2 => two
>>> for each in codes:
	print each

	
1
3
2
>>> codes['1']
'one'
>>> codes['2']
'two'
>>> codes['3']
'three'
>>> codes['4']

Traceback (most recent call last):
  File "<pyshell#11>", line 1, in -toplevel-
    codes['4']
KeyError: '4'
>>>

If you could post your new program, probably be very useful

Mark.

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January 6th, 2004, 03:24 AM

evod510

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here is the script

Code:


blocksize = 88

origfile = open('source.DAT', 'rb')
newfile = open('targer.TXT', 'wb')

while 1:
	datachunk = origfile.read(blocksize)
	if not datachunk:
		newfile.write('end')
		break
	rcd = datachunk[0:1] + ';'
	no = datachunk[1:10] + ';'
	type = datachunk[10:16] + ';'
	date = datachunk[16:28] + ';'
	ref = datachunk[28:40] + ';'
	code = datachunk[40:52] + ';'
	qty = datachunk[52:64] + ';'
	tran1 = datachunk[64:76] + ';'
	tran2 = datachunk[76:88] + ';'

	newfile.write(rcd)
	newfile.write(no)
	newfile.write(type)
	newfile.write(date)
	newfile.write(ref)
	codeLookUp = {'5924  ':'Ball','1015  ':'Pen','6351  ':'Ink','7083  ':'Ruler','5015  ':'Ashtray','7129  ':'Box','5076  ':'Clip')
	newfile.write(codeLookUp[code]) 
	newfile.write(qty)
	newfile.write(tran1)
	newfile.write(tran2)
	

	newfile.write('\r\n')
origfile.close()
newfile.close()

I know something wrong but my knowledge is very limited.

Tq in advance

January 6th, 2004, 04:58 AM

ragabash

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Your slicing code into a 12 character string, right padded with spaces I'm guessing and adding a trailing ';' and then storing it into the variable code. So code acctually looks something like this:

Code:

'1234        ;'

Which is what you want to use as your key if your going to look it up by that whole thing. Or, use:

Code:

newfile.write(codeLookUp[code[:6]])

which will leave code the same, but take the first 6 characters to do a look up in your dictionary.

-rag

Last edited by ragabash : January 6th, 2004 at 05:01 AM.

January 6th, 2004, 07:10 PM

evod510

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tq

i understand what you are saying

kindly can you assist me in the dictionary function

where can i find suitable source/link so i can understand it

more

tq again

January 7th, 2004, 02:35 AM

netytan

Hello World :)

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The dictionary is a type... like lists, strings and tuples! So

, not a function, if anything you'd have to call it a class

. I think thats an important point to get accross here since your gonna be working with OOP eventually.

You can find all the stuff you need to know in the Python tutorial, but here's a link to one dictionary spacific section

http://www.python.org/doc/2.3.3/tut...000000000000000

Take care,
Mark.

#10

January 7th, 2004, 07:37 PM

evod510

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tq for the link

but i found the example a bit confusing

any other link for directory specially with looping condition

tq in advance

#11

January 7th, 2004, 09:57 PM

jimmy2k1

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try reading the first part of this and it'll explain dictionaries http://www.ibiblio.org/obp/thinkCSpy/chap10.htm
I'm not sure how much you'll understand the rest of it though

#12

January 8th, 2004, 02:35 AM

netytan

Hello World :)

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There are actually a few nice examples of looping/iterating over dictionaries in this thread..

http://forums.devshed.com/showthrea...threadid=100130

Mark.

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