byte compiled files

[Mark Robinson]

Thanks for the help guys, sorry I didn't include the code (what can I 
say, duh). Anyway I did manage to fix the problem but I am still kinda 
interested as to why I was getting that previous behaviour. I am running 
python 2.1 under red hat 7, and python 2.1.1 under windows NT and had 
the same problem under both. Here is the code:

def checkValidData(bsite):
	repeats = ['AAAA', 'CCCC', 'GGGG', 'TTTT']
	for x in bsite:	#check new bsite contains valid charactors
		if(x is not 'A' and x is not 'G' and
			x is not 'C' and x is not 'T' ):
			return 0
	for x in repeats:
		if (string.find(bsite, x) != -1):
			return 0
	return 1

Changing where I test if x is A, C, G or T by using the != test rather 
than 'is not' solved the problem, and I guess I may have been using it 
inappropriately, but I still don't see why it would have working 
correctly first run and then incorrectly when working from the .pyc file.

Blobby

Mark Robinson wrote:

> can anyone shed some light on the mysterious behaviour of my byte 
> compiled files. I am currently working on a python script which analyses 
> patterns in a DNA sequence. I have a function which checks a pattern (a 
> substring of approx 6 chars) to ensure only valid charactors are 
> present. When I first run this program it runs fine, but if I 
> immediately rerun the program (i.e using the pre-byte compiled file) it 
> finds all patterns non-valid. If I delete the .pyc file between runs 
> this problem does not occur. Can anyone explain what is happening here 
> to me and how to prevent it?
> 
> blobby