Prints on stdout but unable to write to file in Python

Question

I'm really frustrated with this strange behaviour of Python all of a sudden. I've been writing to files all sorts of data but since today morning it just doesn't seem to work. I've referred to all these before posting:

Have tried all following commands but it just doesn't write anything to the delete.txt file. What's happening?

fl=open('delete.txt','w')
fl.write(msg) <--Doesnt work,tried this also
fl.write('%s' %msg) <--Doesnt work,tried this also
fl.write("at least write this") <-- Doesnt work,tried this also
print (msg) <- WORKS

Code:

for i in hd_com.comment_message[1:500]:
fl=open('delete.txt','wb')

try:
    if len(i)>40:
        mes=processComUni(i)
        proc=nltk.tokenize.word_tokenize(mes)
        #print proc
        pos=nltk.pos_tag(proc)
        for i in pos:
            if ((i[1]=="NN") or (i[1]=="NNP") or (i[1]=="NNS")) and len(i[0])>2:
                #print i[0],i[1]
                for j in home_depo_inv:
                    if i[0] in j.split() and (i[0]!='depot' and i[0]!='home' and i[0]!='store' and i[0]!='por' and i[0]!='get' and i[0]!='house' and i[0]!='find' and i[0]!='part' and i[0]!='son' and i[0]!='put' and i[0]!='lot' and i[0]!='christmas' and i[0]!='post'):
                        a=re.findall(i[0],j)
                        fl.write(str(i))<--Doesnt work,tried this also
                        fl.write(str(mes))<--Doesnt work,tried this also
                        fl.write("\n")<--Doesnt work,tried this also
                        fl.write("hello")<--Doesnt work,tried this also
                        fl.flush()
                        break
except:
    continue
fl.close()

More code:

type(mes) = str
mes="omg would love front yard"

no errors on console. Why is it that prints working fine, but its not writing the same to a file ? — , Dec 09 '14 at 06:22
type(msg)=str, os=win8, editor=ipython. This strange error for the first time since working on python — , Dec 09 '14 at 06:26
What Python version? Did you close the file before attempting to verify its contents? — PM 2Ring, Dec 09 '14 at 06:29
Refresh the page, I already solved your issue in an answer below =) — Riku L, Dec 09 '14 at 06:36
did you try with another file ? create another file and try with ! and give us the result ! — Mazdak, Dec 09 '14 at 06:39
@Kasra checked again ,now its writing only the last message (mes) to the file. Not writing the previous lines. I guess they are getting overwritten or something — , Dec 09 '14 at 06:42
so good , how you write `msg` to file ? and whats it look like ? — Mazdak, Dec 09 '14 at 06:43
Pls see my code that Ive added in question. Thats how im writing mes to file — , Dec 09 '14 at 07:17
Change the `except:` to `except Exception as exp:` and then print the except out (rather than ignoring it). — martineau, Dec 09 '14 at 08:02

score 3 · Accepted Answer · answered Dec 09 '14 at 08:31

Your snippet's indentation is totally messed up, but anyway: your code starts with:

for i in hd_com.comment_message[1:500]:
    fl=open('delete.txt','wb')

which means you reopen the file for writing on each iteration, erasing whatever might have been written by the previous iteration.

score 1 · Answer 2 · answered Dec 09 '14 at 06:27

1

You need to flush the output stream explicitly when writing to a file handle like that.

f = open("test.txt", "w")
f.write("this is a test\n")
# no text in the output file at this point
f.flush()
# buffers are flushed to the file
f.write("this, too, is a test\n")
# again, line doesn't show in the file
f.close()
# closing the file flushes the buffers, text appears in file

From the documentation of file.write:

Note that due to buffering, flush() or close() may be needed before the file on disk reflects the data written.

answered Dec 09 '14 at 06:27

Riku L

367
3
9

Doesnt work either, have updated my code with your suggestions in question, still no luck – Dec 09 '14 at 06:37
its writing only the last message (mes) to the file. Not writing the previous lines. I guess they are getting overwritten or something. Whats even happening here. – Dec 09 '14 at 08:16

Prints on stdout but unable to write to file in Python

2 Answers2