Python: Problem with if statement

Question

I have problem with a if statement code below:

do_blast(x):
    test_empty = open('/home/rv/ncbi-blast-2.2.23+/db/job_ID/%s.blast' % (z), 'r')
        if test_empty.read() == '':
            test_empty.close()
            return 'FAIL_NO_RESULTS'
        else:
            do_something

def return_blast(job_ID):
     if job_ID == 'FAIL_NO_RESULTS':
        return '<p>Sorry no results :( boooo</p>'
    else:
        return open('/home/rv/ncbi-blast-2.2.23+/db/job_ID/job_ID_%s.fasta' % (job_ID), 'r').read()

For some reason the code tries to assign "job_ID" to the fasta file in return_blast even though it should have returned "sorry no results". I also understand the file names and extensions are different i have my reasons for doing this.

The code works perfectly when the test_empty file is not empty.

@Tim, I changed the indentation because it was misleading (and indentation is everything in python) — Brendan Long
– Brendan Long, Commented Jul 17, 2010 at 3:32
@Tim, the indentation in the code you posted was all wrong, so it's impossible to understand your problem. Please check it and edit your Q (hint: don't use tabs -- indent with four spaces per level only). Not sure @Brendan correctly read your mind in his indentation edit, since your problem might easily be connected to wrong indents (depending, as @Greg rightly asks, on how the two seemingly isolated functions actually "connect"). — Alex Martelli
– Alex Martelli, Commented Jul 17, 2010 at 3:32
I didn't even notice the indentation in the second function. I would fix it too but it might be the cause of your error.. I reverted my previous edit just in case. — Brendan Long
– Brendan Long, Commented Jul 17, 2010 at 3:33
do_blast returns a integer (job_ID) if the file is not empty which is then retrieved from a URL by form.getfirst and passed through to return_blast — Tim
– Tim, Commented Jul 17, 2010 at 3:35

Brendan Long · Accepted Answer · 2010-07-17 03:36:51Z

1

I'm not sure if this is the problem, but your code isn't indented correctly (and that matters in Python). I believe this is what you were wanting:

do_blast(x):
    test_empty = open('/home/rv/ncbi-blast-2.2.23+/db/job_ID/%s.blast' % (z), 'r')
    if test_empty.read() == '':
        test_empty.close()
        return 'FAIL_NO_RESULTS'
    else:
        do_something

def return_blast(job_ID):
    if job_ID == 'FAIL_NO_RESULTS':
        return '<p>Sorry no results :( boooo</p>'
    else:
        return open('/home/rv/ncbi-blast-2.2.23+/db/job_ID/job_ID_%s.fasta' % (job_ID), 'r').read()

I don't think your code would have even run though..

answered Jul 17, 2010 at 3:36

Brendan Long

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2 Comments

Tim Over a year ago

The code is indented correctly if my file. It runs when the file is not empty but fails to catch when the file is.

Brendan Long Over a year ago

@Tim, please fix it in the question too so we know how your code actually looks.

ars · Accepted Answer · 2010-07-17 18:46:16Z

0

Maybe some simple printf style debugging will help:

def return_blast(job_ID):
    print 'job_ID: ', job_ID
    # ...

Then you can at least see what "job_ID" your function receives. This is crucial for trying to figure out why your if statement fails.

answered Jul 17, 2010 at 18:46

ars

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