Conditional Field issue in Python with CSV File

Question

This is my code thus far:

with open('in.csv', 'rb') as inp, open('out.csv', 'wb') as out:
    writer = csv.writer(out)
    for row in csv.reader(inp):
        try:
            floatRow= float(row[3].strip())
            if  floatRow > 180.0:
                row[3] = floatRow - 180.0
                writer.writerow(row)
            else:
                if floatRow < 180.0:
                    row[3] = floatRow + 180.0
                else:
                    writer.writerow(row)

        except ValueError,e:
            writer.writerow(row)

The issue comes in the if/else statement. The 'if' statement works (as in the subtraction of 180), whereas the else statement will not work. The script runs fine, but it will eliminate all records with a value under 180 for some reason.

Where am I going wrong and how can I resolve this?

Anshul Goyal · Accepted Answer · 2015-04-20 03:35:33Z

3

You don't write the row (writer.writerow(row) is missing) for that if block

if floatRow < 180.0:
    row[3] = floatRow + 180.0
    writer.writerow(row) # This is missing
else:
    writer.writerow(row)

Note: Since you are using if-else mainly to alter data for the row[3] column, I would suggest simplifying your script by moving the writer.writerow statements out and keeping only that altering logic within if-elif blocks

with open('in.csv', 'rb') as inp, open('out.csv', 'wb') as out:
    writer = csv.writer(out)
    for row in csv.reader(inp):
        try:
            floatRow= float(row[3].strip())
            if  floatRow > 180.0:
                row[3] = floatRow - 180.0
            elif floatRow < 180.0:
                row[3] = floatRow + 180.0
            writer.writerow(row)
        except ValueError,e:
            writer.writerow(row)

edited Apr 20, 2015 at 3:35

answered Apr 20, 2015 at 3:28

Anshul Goyal

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4 Comments

Will B Over a year ago

That hurts my pride that I did not notice that. second pair of eyes are sometimes needed. Thank you.

Anshul Goyal Over a year ago

@WillB We all make silly mistakes. Anyway, also check the edit.

Will B Over a year ago

I originally had it as your edit, but I was trying all sorts of different ways to make the if/else work because I was dumbfounded as to why it wasn't working. Thanks again!

Anshul Goyal Over a year ago

@WillB If your query was resolved, don't forget to accept this ;)

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