Question

I am trying to find entries with specific zip codes in a mailing list (CSV format).
I thought this should work but it never finds anything despite my knowing that the sought after zip codes are there.

text = open("during1.txt","r")
a = list(range(93201,93399))
b = list(range(93529,93535))
c = list(range(93601,93899))
d = list(range(95301,95399))
KFCFzip = a+b+c+d
output = open("output.txt","w")

for line in text:
    array= line.strip().split(",")
    print(array[6][0:5])
    if array[6][0:5] in KFCFzip:
        #output.write(array)
        print("yes")
text.close()
output.close()

When I run the code, it finds no matches, but the print statement above the IF statement prints out values that look like they should be matches, and when I go to the Shell and type in something like

93701 in KFCFzip

It gives me back “True:, so it’s work to that extent. The file is just text separated by commas, so I can’t figure out why it can see them.
The data file has live data, so I would have to change it a bit before posting. I was wondering if anyone had any ideas that didn’t involve posting the data itself.

Answer 1

Because array[6][0:5] is the string. You should convert it to the integer before looking at the KFCFzip list.

for line in text:
    array= line.strip().split(",")
    print(array[6][0:5])
    if int(array[6][0:5]) in KFCFzip:
        print("yes")

Another problem with this solution is the performance. range creates a list of elements so you are going to compare every “suspected” ZIP code with every possible zip code. Time complexity for this algorithm is O(n*m) where n = len(KFCFzip) and m – number of lines in the file. Better way is to create a list of ranges like:

KFCFzip = [[93201,93399], [93529,93535], [93601,93899], [95301,95399]]

for line in text:
    array= line.strip().split(",")
    zip = int(array[6][0:5]))
    print(zip)
    found = False
    for r in KFCFzip:
        if zip >= r[0] and zip < r[1]:
            found = True
            break
    if found:
        print("yes")

in this case you can dramatically increase the performance.

For instance using your data you would have 197+5+297+97 = 596 elements, so for each line you would have to make 596/2 = 298 comparisons in average. But using my algorithms you’ll have only 8/2 = 4 comparisons, which ~ 75 times less (read faster).