Limiting the searching of a large file
<p>So here is my program with some new modifications:</p>

<pre><code>datafile = open('C:\\text2.txt', 'r')
completedataset = open('C:\\bigfile.txt', 'r')
smallerdataset = open('C:\\smallerdataset.txt', 'w')
matchedLines = []
for line in datafile:
    splitline = line.split()
    for item in splitline:
        if not item.endswith("NOVA"):
            if item.startswith("JJJ") or item.startswith("KOS"):
                matchedLines.append( item )
counter = 1
for line in completedataset:
    print counter
    counter +=1
    for t in matchedLines:
        if t in line:
            smallerdataset.write(line)
datafile.close()
completedataset.close()
smallerdataset.close()
</code></pre>

<p>The problem that I have now is that I want to search through the "bigfile" but at a faster rate. I would like to limit the searching of each line in bigfile to the string that occurs before the first ','</p>

<p>I want to use something like index = aString.find(',') I beleive but I'm not having much luck limiting the search of the big file to the string that occurs before the first comma.  </p>
