1

I have a small code snippet and need help implementing a fail statement (No match). Here is the snippet:

for row in reader:
    # converts each string num --> int num
    i = 1
    while i < len(row):
        row[i] = int(row[i])
        i += 1

    if STR_count_large(sequence) == row[1:]:
        print(row[0])

    if STR_count_small(sequence) == row[1:]:
        print(row[0])

I iterate through each row in a csv file called reader, and convert each element in that row from a string to an int. After that, I compare the contents of the list of that particular row (from the 1st element to the end) against two functions that each contain a list. If the two lists match, I print row[0], which simply contains the name of the person who the matching list belongs to. However, if both of these if statements fail after going through the for row in reader: loop, how would I go about printing a statement like No match only once? Because if I write it inside the loop, this statement would be printed row number of times rather than just once.

EDIT: Here is my (unsuccessful) implementation using bschlueter's idea. Any help would be greatly appreciated:

exceptions = list()
            for row in reader:
                # converts each string num --> int num
                i = 1
                while i < len(row):
                    row[i] = int(row[i])
                    i += 1
                try:
                    if STR_count_large(sequence) == row[1:]:
                        print(row[0])
                    if STR_count_small(sequence) == row[1:]:
                        print(row[0])
                except (STR_count_large(sequence) != row[1:] and STR_count_small(sequence) != row[1:]) as exception:
                    exceptions.append(exception)
            if exceptions:
                print("No match")
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2 Answers 2

Reset to default
1

You could accumulate errors, then check the accumulation after the completion of the loop:

exceptions = list()
for row in reader:
    try:
        do_a_thing(row)
    except MyException as exception:
        exceptions.append(exception)
# Do something if any exceptions were added to the list
if exceptions:
    handle_exceptions(exceptions)
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2 Comments

What would be the proper way to implement this? I tried using this structure, but I do not have much familiarity with try and except in python. I've added an edit to my original post that shows my version of trying to implement this based on your suggestion.
The function do_a_thing needs to throw MyException. Exception handling in python is fairly simple, just go search for the docs. It looks like you'd be better off just using an if statement though, with a boolean value rather than the accumulator list.
0

Just add one more if statement with and for catching and printing no match. add this at the end of second IF statement

if row == reader[len(reader)]:#Check for last iteration
    if STR_count_large(sequence) != row[1:]: and STR_count_small(sequence) != row[1:]:
        print("No Match")
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4 Comments

The problem with this is that it will print the No match statement row number of times (which in this case would be three times). I only want to print the No match statement once.
i have edited code to check for last iteraiton based on length of reader
Sorry, this also does not work because you cannot call len() on reader because it is a csv. Thank you for trying though
stackoverflow.com/a/2429260/10849457 This will help you

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