python writing to a file

Question

I keep getting this "writing to a closed file error" while trying to compile the following code:

fout = open('markov_output.txt', 'w') for i in range( MAXGEN ) : # get our hands on the list key = (w1,w2) sufList = table[key] # choose a suffix from the list suf = random.choice( sufList ) if suf == NONWORD : # caught our "end story" marker. Get out if len( line ) > 0 : fout.write(line) break if len( line ) + len( suf ) > MAX_LINE_LEN : fout.write(line) line = "" line = line + " " + suf w1, w2 = w2, suf fout.close()

Why are you closing the file inside the loop? That would probably only write one record and then the file would be closed. Is that what you intended? Or is your indentation wrong? — S.Lott
– S.Lott, Commented Dec 6, 2010 at 18:23

Glyph · Accepted Answer · 2010-12-06 18:23:01Z

5

You're closing fout each time through the loop. Un-indent fout.close() and it should work as expected.

answered Dec 6, 2010 at 18:23

Glyph

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1 Comment

user225312 Over a year ago

And because he is Glyph, another +1 ;)

Fred Larson · Accepted Answer · 2010-12-06 18:22:59Z

Don't you want the fout.close() outside the loop??

You might want to consider using with if you have Python 2.5 or newer:

with open('markov_output.txt', 'w') as fout: # Your code to write to the file here

That will automatically close the file when you're done, as well as if any exceptions occur.

Note that in Python 2.5 you have to use from __future__ import with_statement.

jgritty · Accepted Answer · 2010-12-06 18:23:22Z

fout.close() seems to be inside the for loop.

Un-indent that line, for the intended behavior.

Yann Ramin · Accepted Answer · 2010-12-06 18:24:06Z

Your fout.close() occurs inside the for loop. It will be closed after the first item, not at the end of the operation.

For clarity/robustness, it is recommended to use the with operator when dealing with files.

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