Ignore StopIteration

Question

I just read a bunch of posts on how to handle the StopIteration error in Python, I had trouble solving my particular example, though. Basically, I have a csv file with a lot of prefixes. This file has two columns with headers: Word and Count. Count is the frequency with which that prefix occurs. I also have another file with a list of company names. The prefix file acquired the prefixes from the first word of each company name in the company file. I'm trying to remove duplicates, and what I want to do right now is :

Ignore the StopIteration error every time this error would occur.

In order words, instead of having to write all the commented out "if" statements below, I just want one line that says: if a StopIteration error is generated, simply ignore the error is some way by treating the problematic "prefix" as if it were a prefix which occurs more than twice in the prefix file, such that we should return the value of the company name without the prefix included. I realize that this ignores the fact that there is a different prefix value in the prefix file and the actual prefix of the company name, but usually it has to do with non-American English letters stored differently between python and excel, and a few other ways that don't seem particularly systematic so I'll just remove them manually later.

My code is:

def remove_prefix(prefix, first_name):
   #try:
   #EXCEPTIONS:
   #if '(' in prefix:
   #    prefix = prefix[1:]
      #if ')' in prefix:
    #  prefix = prefix[:-1]
    """
      if prefix == "2-10":
        prefix = "2"
      if prefix == "4:2:2":
        prefix = "4"
      if prefix == "5/0" or prefix == "5/7" or prefix == "58921-":
        prefix = "5"
    """
    #except StopIteration:
   #    pass

   print(first_name, prefix)
   input_fields = ('Word', 'Count')
   reader = csv.DictReader(infile1, fieldnames = input_fields)
   #if the prefix has a frequency of x >=2 in the prefix file, then return first_name  without prefix
   #else, return first_Name
   infile1.seek(0)
   #print(infile1.seek(0))
   next(reader)
   first_row = next(reader)
   while prefix != first_row['Word'] and prefix[1:]!= first_row['Word']:
      first_row = next(reader)
      #print(first_name, prefix)
      #print(first_row, first_name, prefix, '\t' + first_row['Word'], prefix[1:])
   if first_row['Count'] >= 2:
      length = len(prefix)
      first_name = first_name[length+1:]
  #print("first name is ", first_name)
  return first_name

Answer 1

I don't think this is caused by what you think it is caused by. The StopIteration exception is caused when the generator (reader) runs out of lines to read.

For example:

def g():
    "generates 1 (once)"
    yield 1

a = g()
next(a) # is 1
next(a) # StopIteration exception (nothing left to yield)

To fix this you can wrap the next in a try, except (pass):

while prefix != first_row['Word'] and prefix[1:]!= first_row['Word']:
    try:
        first_row = next(reader)
    except StopIteration:
        pass

However, as David points out, this is probably not the way you ought to be going about this.