running same script on same data on two different machines --> different result

[Philip Semanchuk]

On Nov 14, 2008, at 10:14 AM, Christopher Brewster wrote:

> I am running the same script on the same data on two different
> machines (the folder is synchronised with Dropbox).
> I get two different results. All the script does is count words in
> different files and perform a simple set operation on the word lists.
> The laptop is a Macbook Pro (2 1/2 years old) running OS X 10.5.5 with
> Python 2.5.1
> The desktop is an iMac (brand new) running OS X 10.5.5 also with
> Python 2.5.1
>
> I have tried running the script on an ubuntu server with Python 2.5.2
> and the results corresponded with my laptop's output.
> How can I find out the cause of this anomaly? What tests can I
> perform?

No idea what Dropbox is, but it is a potential point of failure.  
Ensure it is doing its job. Programmatically ensure that the source  
files are exactly the same before you start your Python program.

Then try your program on different source files. If the problem shows  
up on some source files and not on others, try to figure out the  
pattern that relates the files.

Or take your "problem" data file and chop it in half by deleting the  
lines from the first half of the file. See if the problem still  
occurs. If not, try using the latter half of the file. By using a  
binary search like this, maybe you can isolate the problem data to a  
very small portion making visual detection of the problem easier.

Until you get more info, this is just generic debugging and isn't  
specific to Python.

Good luck
Philip