python - Fastest Text search method in a large text file

Question

I am doing a text search in a rather big txt file (100k lines, 7mo) Text is not that big but I need a lot of searches. I want to look for a target string and return the line where it appears. My text file is formatted so that the target can only appear in one line.

What is the most efficient way? I do a lot of searches so I want to improve speed. Here is mycode right now:

def lookup_line(target):
    #returns line of the target, or None if doesnt exist
    line=None
    dir=os.path.dirname(__file__)
    path=dir+'/file.txt'
    file=open(path,'r')
    while line==None:
        l=file.readline()
        l=unicode(l,'utf-8')
        if target in l:
            break
        if l=='': break #happens at end of file, then stop loop
    line=l
    if line=='':line=None #end of file, nothing has been found
    file.close()
    return line

I use this python code for a google Appengine app.

Thanks!

Answer 1

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