String processing inside lists

[Gary Moore]

After diligently  and successfully going through 'Programming Python'  I
decided that a good first project would be to take my DVD collection (228
Discs) and build three different files (a tab delimited file for import into
a database, an xml file for each movie, and a text file for each movie). I
decided to gather the information from the Internet movie database .list
files and then process and sort the output in python.

The problem happened when I tried to use the construct:

    for x in actors

to process the list of actors prior to output.

When I use the string library to process this list, I want the actual
strings contained in the list to change. What I found was that no matter how
I tried to change the strings in the actors list, I was unsuccessful. e.g.

temp = replace(x,'\012','')
x = temp

When I print x, I get the line with the text replaced. However, when I view
the line in the original array actors, the changes were not made.

The only way I could overcome this problem was to change the for statement
to:

    for x in range(len(actors))

and then subscript the actors list to obtain the results e.g.

temp = replace(actors[x],'\012','')
actors[x] = temp

My concern is that I must not be understanding some basic concept concerning
the FOR loop in Python. I reread the material in 'Learning Python', but
still could not understand why the first solution above did not work.

I fnally completed a working prototype and successfully carried out the
conversion of all of the information. It was amazingly fast, and I was very
impressed with the power available with a minimum of effort (1 day).

If anyone could clarify the situation above, I would appreciate it.

Thanks,

Gary Moore
moore at oakland.edu
Mount Clemens, Michigan, USA

PS Sorry about the long message. :)