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Can anyone help me with what does this part of python code mean?

I would like to know what this small portion of code means, because it seems like in the file that the script creates it adds a line in the end and i believe it might be one of those symbols
opened_file.write("%s\n" %user_input)

It writes a line. The content of user_input replaces the %s (see string interpolation in the docs) and \n is the newline character - after user_input.
Here is a good description of the different "inserting data into strings" methods, including % interpolation (which is now considered outdated):
https://realpython.com/python-string-formatting/

having spacing issues in using "\n" in a separate file

e.write("y.write('\n+d')")
I was trying to write this line of code into a separate python program
y.write('\n'+d)
and when it wrote it, it went like this
str.write('
'+d)
but the '+d) was up one space above this text
any suggestions to keep it in the same line?

e.write("y.write('\\n'+d)")
(escape the backslash to make it a literal character), or:
e.write(r"y.write('\n'+d)")
(use a raw string to make backslashes not special).

Format string confusing

Hi im new to Python and Ive been trying to get format print to work but, and this may be me being new, but it seems to be very badly implemented.Any examples for 2.7.6 dont work for the new version and their aren't any real examples I could find on the internet for 3.3. As such I would like to ask for a good example of how format string works. For instance ive been trying to get this to work from my homework.
day,date,year,hour,and minutes must be separate variables.
using one formatted print statement,print the following:
Date:5/31/2013
Time: 3:45 pm
I can get it to work with this code:
def date():
Month=5
Day=31
Year=2013
Hours=3
Minutes=45
Scale='pm'
a="Date: %i/%i/%i\nTime: %i:%i %s" %(Month,Day,Year,Hours,Minutes,Scale)
print(a)
It works but its not one line as asked for. Please help format is so confusing.

The \n in your format string is inserting the new line character. Remove the \n, and you will not have the newline any longer.
Characters preceded by a backslash are known as escape characters. They can be used to insert special formatting into strings. For example:
\n is the newline character,
\t is the tab character

Remove \n because that is used to create a line break.

Extract Text from a Binary File (using Python 2.7 on Windows 7)

I have a binary file of size about 5MB.. which has lots of interspersed text.. and control characters..
This is actually an equivalent of an outlook .pst file for SITATEX Application (from SITA).
The file contains all the TEXT MESSAGES sent and received to and from outside world...(but the text has to be extracted through the binary control characters).. all the text messages are clearly available... with line ending ^M characters... etc.
for example: assume ^# ^X are control characters... \xaa with HEX aa, etc. loads of them around my required text extraction.
^#^#^#^#^#^#^#^#^#^#^#BLLBBCC^X^X^X^X^X^X^X^X^X
^X^X^X
MVT^M
EA1123 TEXT TEXT TEXT^M
END^M
\xaa^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#^#
^#^#^#^#^#^#^#^#^#^#^#TTBBTT^X^X^X^X^X^X^X^X^X
^X^X^X blah blah blah... of control characters.. and then the message comes..
MVT MESSAGE 2
ED1123
etc.
and so on.. for several messages.
Using Perl.. it is easy to do:
while (<>) {
use regular expression to split messages
m/ /
}
How would one do this in python easily..
How to read the file? binary and text interspersed
Eliminate unnecessary control characters
parse the messages in between two \xaa USEFUL TEXT INFORMATION \xaa (HEX 'aa')
print out the required stuff
Loop through all the lines.. and more files.
In the text file sample... I am interested in seeing.. BLLBBCC... and MVT and EA1123 and so on.
Please assist... If it is going to be very difficult in python.. I will have to think through the logic in perl itself.. as it (perl) doesn't throw lots of errors at me at least for the looping part of binary and text stuff.. and the regex.
Thanks.
Update 02Jan after reading your answers/comments
After going through S.Lott's comments and others... This is where I am at.. and it is working 80% ok.
import fileinput
import sys
import re
strfile = r'C:\Users\' \
r'\Learn\python\mvt\sitatex_test.msgs'
f = open(strfile, 'rb')
contents = f.read() # read whole file in contents
#extract the string between two \xaaU.. multiline pattern match
#with look ahead assertion
#and this is stored in a list with all msgs
msgs = re.findall(r'\xaaU.*?(?=\xaaU)', contents, re.I|re.DOTALL|re.M)
for msg in msgs:
#loop through msgs.. to find the first msg then next and so on.
print "## NEW MESSAGE STARTS HERE ##"
#for each msg split the lines.. to read line by line
# stored as list in msglines
msglines = msg.splitlines()
line = 0
#then process each msgline with a message
for msgline in msglines:
line += 1
#msgline = re.sub(r'[\x00]+', r' ', msgline)
mystr = msgline
print mystr
textstrings = re.findall(r'[\x00\x20-\x7E]+', msgline)
So far so good.. still I am not completely done.. because I need to parse the text line by line and word by word.. to pickup (as an example) the origin address and headers, subject line, message body... by parsing the message through the control characters.
Now I am stuck with... how to print line by line with the control characters converted to \x00\x02.. etc (using the \xHH format).. but leave the normal readable text alone.
For example.. say I have this: assume ^# and ^X are some control characters
line1 = '^#UG^#^#^#^#^#^#^#^#^#^#BLLBBCC^X^X^X^X^X^X^X^X^X' (on the first line).
When I print the line as it is on IDLE.. print line1.. it prints only say the first 2 or 3 characters.. and ignores the rest due to the control characters get choked.
However, when I print with this: print re.findall(r'.*', line1)
['\xaaUG\x02\x05\x00\x04\x00\x00\x00\x05\x00\x00\x00....
x00\x00\x00..BLLBBCC\x00\x00N\x00N\\x00
002 010 180000 DEC 11', '']
It prints nicely with all the control characters converted to \xHH format.. and ascii text intact.. (just as I want it)..with one catch.. the list has two items.. with '' in the end.
What is the explanation for the empty string in the end?
How to avoid it... I just want the line converted nicely to a string (not a list). i.e. one line of binary/text to be converted to a string with \xHH codes.. leave the ASCII TEXT alone.
Is using re.findall(r'.*', line1) is the only easy solution.. to do this conversion.. or are there any other straightforward method.. to convert a '\x00string' to \xHH and TEXT (where it is a printable character or whitespace).
Also.. any other useful comments to get the lines out nicely.
Thanks.
Update 2Jan2011 - Part 2
I have found out that re.findall(r'.+', line1) strips to
['\xaaUG\x02\x05\x00\x04\x00\x00\x00\x05\x00\x00\x00....
x00\x00\x00..BLLBBCC\x00\x00N\x00N\\x00
002 010 180000 DEC 11']
without the extra blank '' item in the list. This finding after numerous trial and errors.
Still I will need assistance to eliminate the list altogether but return just a string.
like this:
'\xaaUG\x02\x05\x00\x04..BLLBBCC..002 010 180000 DEC 11'
Added Info on 05Jan:
#John Machin
1) \xaaU is the delimiter between messages.. In the example.. I may have just left out in the samples. Please see below for one actual message that ends with \xaaU (but left out).
Following text is obtained from repr(msg between r'\xaaU.*?(?=\xaaU)')
I am trying to understand the binary format.. this is a typical message which is sent out
the first 'JJJOWXH' is the sender address.. anything that follows that has 7 alphanumeric is the receiver addresses.. Based on the sender address.. I can know whether this is a 'SND' or 'RCV'.. as the source is 'JJJOWXH'... This msg is a 'SND' as we are 'JJJOWXH'.
The message is addressed to: JJJKLXH.... JJJKRXH.... and so on.
As soon as all the.. \x00000000 finishes..
the sita header and subject starts
In this particular case... "\x00QN\x00HX\x00180001 \x00" this is the header.. and I am only interested all the stuff between \x00.
and the body comes next.. after the final \x00 or any other control character... In this case... it is:
COR\r\nMVT \r\nHX9136/17.BLNZ.JJJ\r\nAD2309/2314 EA0128
BBB\r\nDLRA/CI/0032/0022\r\nSI EET 02:14 HRS\r\n RA / 0032 DUE TO
LATE ARVL ACFT\r\n CI / 0022 OFFLOAD OVERHANG PALLET DUE INADEQUATE
PACKING LEADING TO \r\n SPACE PROBLEM
once the readable text ends... the first control character that appears until the end \xaaU is to be ignored... In above cases.. "SPACE PROBLEM".. is the last one.. then control characters starts... so to be ignored... sometimes the control characters are not there till the next \xaaU.
This is one complete message.
"\xaaU\x1c\x04\x02\x00\x05\x06\x1f\x00\x19\x00\x00\x00\xc4\x9d\xedN\x1a\x00?\x02\x02\x00B\x02\x02\x00E\x02\x07\x00\xff\xff\x00\x00\xff\xff\x00\x00\xff\xff\x00\x00M\x02\xec\x00\xff\xff\x00\x00\x00\x00?\x02M\x02\xec\x00\xff\xff\x00\x00\xff\xff\x00\x00\xff\xff\x00\x00\xff\xff\x00\x00\xff\xff\x00\x00:\x03\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x7f\x00JJJOWXH\x00\x05w\x01x\x01\x00\x01JJJKLXH\x00\x00\x7f\x01\x80\x01\x00\x01JJJKRXH\x00F\x87\x01\x88\x01\x00\x01JJJFFXH\x00\xff\x8f\x01\x90\x01\x00\x01JJJFCXH\x00\xff\x97\x01\x98\x01\x00\x01JJJFAXH\x00\x00\x9f\x01\xa0\x01\x00\x01JJJKPXH\x00\x00\xa7\x01\xa8\x01\x00\x01HAKUOHU\x00\x00\xaf\x01\xb0\x01\x00\x01BBBHRXH\x00\x00\xb7\x01\xb8\x01\x00\x01BBBFFHX\x00\x00\xbf\x01\xc0\x01\x00\x01BBBOMHX\x00\x00\xc7\x01\xc8\x01\x00\x01BBBFMXH\x00\x00\xcf\x01\xd0\x01\x00\x01JJJHBER\x00\x00\xd7\x01\xd8\x01\x00\x01BBBFRUO\x00\x00\xdf\x01\xe0\x01\x00\x01BBBKKHX\x00\x00\xe7\x01\xe8\x01\x00\x01JJJLOTG\x00\x01\xef\x01\xf0\x01\x00\x01JJJLCTG\x00\x00\xf7\x01\xf8\x01\x00\x01HDQOMTG\x005\xff\x01\x00\x02\x00\x01CHACSHX\x00K\x07\x02\x08\x02\x00\x01JJJKZXH\x00F\x0f\x02\x10\x02\x00\x01BBBOMUO\x00
\x17\x02\x18\x02\x00\x01BBBORXH\x00 \x1f\x02
\x02\x00\x01BBBOPXH\x00W'\x02(\x02\x00\x01CHACSHX\x00
/\x020\x02\x00\x01JJJDBXH\x0007\x028\x02\x00010000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00\x00000000\x00QN\x00HX\x00180001
\x00COR\r\nMVT \r\nHX9136/17.BLNZ.JJJ\r\nAD2309/2314 EA0128
BBB\r\nDLRA/CI/0032/0022\r\nSI EET 02:14 HRS\r\n RA / 0032 DUE TO
LATE ARVL ACFT\r\n CI / 0022 OFFLOAD OVERHANG PALLET DUE INADEQUATE
PACKING LEADING TO \r\n SPACE
PROBLEM\x00D-\xedN\x00\x04\x1a\x00t<\x93\x01x\x00M_\x00"
2) I am not using .+ anymore after the 'repr' is known.
3) each Message is multiline.. and i need to preserve all the control characters to make some sense of this proprietary format.. that is why i needed repr to see it up close.
Hope this explains... This is just 1 message out of 1000s with in the file... and some are 'SND' and some are 'RCV'... and for 'RCV' there will not be '000000'.. and occasionally there are minor exceptions to the rule... but usually that is okay.
Any further suggestions anyone.. I am still working with the file.. to retrieve the text out intact... with sender and receiver addresses.
Thank you.

Python supports regexes too. I don't speak Perl, so I don't know exactly what your Perl code does, but this Python program might help you:
import re
with open('yourfile.pst') as f:
contents = f.read()
textstrings = re.findall(r'[\x20-\x7E]+', contents)
That will get you a list of all strings of one or more ASCII printable characters in the file. That may not be exactly what you want, but you might be able to tweak it from there.
Note that if you're using Python 3, then you have to worry about the distinction between binary and textual data and it becomes a bit more complicated. I'm assuming you're in Python 2.

Q: How to read the file? binary and text interspersed
A: Don't bother, just read it as normal text and you'll be able to keep your binary/text dichotomy (otherwise you won't be able to regex it as easily)
fh = open('/path/to/my/file.ext', 'r')
fh.read()
Just in case you want to read binary later for some reason, you just add a b to the second input of the open:
fh = open('/path/to/my/file.ext', 'rb')
Q: Eliminate unnecessary control characters
A: Use the python re module. Your next question sorta ask how
Q: parse the messages in between two \xaa USEFUL TEXT INFORMATION \xaa (HEX 'aa')
A: re module has a findall function that works as you (mostly) expect.
import re
mytext = '\xaaUseful text that I want to keep\xaa^X^X^X\xaaOther text i like\xaa'
usefultext = re.findall('\xaa([a-zA-Z^!-~0-9 ]+)\xaa', mytext)
Q: print out the required stuff
*A: There's a print function...
print usefultext
Q: Loop through all the lines.. and more files.
fh = open('/some/file.ext','r')
for lines in fh.readlines():
#do stuff
I'll let you figure out the os module to figure out what files exist/how to iterate through them.

You say:
Still I will need assistance to eliminate the list altogether but return just a string. like this
In other words, you have foo = [some_string] and you are doing print foo which as a side does repr(some_string) but encloses it in square brackets which you don't want. So just do print repr(foo[0]).
There seem to be several things unexplained:
You say the useful text is bracketed by \xaaU but in the sample file instead of 2 occurrences of that delimiter there is only \xaa (missingU) near the start, and nothing else.
You say
I have found out that re.findall(r'.+', line1) strips to ...
That in effect is stripping out \n (but not \r!!) -- I thought line breaks would be worth preserving when attempting to recover an email message.
>>> re.findall(r'.+', 'abc\r\ndef\r\n\r\n')
['abc\r', 'def\r', '\r']
What you you done with the \r characters? Have you tested a multi-line message? Have you tested a multi-message file?
One is left to guess who or what is intended to consume your output; you write
I need to parse the text line by line and word by word
but you seem overly concerned with printing the message "legibly" with e.g. \xab instead of gibberish.
It looks like the last 6 or so lines in your latest code (for msgline in msglines: etc etc) should be indented one level.
Is it possible to clarify all of the above?

Cleaning an XML file in Python before parsing

I'm using minidom to parse an xml file and it threw an error indicating that the data is not well formed. I figured out that some of the pages have characters like ไอเฟล &, causing the parser to hiccup. Is there an easy way to clean the file before I start parsing it? Right now I'm using a regular expressing to throw away anything that isn't an alpha numeric character and the </> characters, but it isn't quite working.

Try
xmltext = re.sub(u"[^\x20-\x7f]+",u"",xmltext)
It will get rid of everything except 0x20-0x7F range.
You may start from \x01, if you want want to keep control characters like tab, line breaks.
xmltext = re.sub(u"[^\x01-\x7f]+",u"",xmltext)

Take a look at µTidyLib, a Python wrapper to TidyLib.

If you do need the data with the strange characters you could, in stead of just stripping them, convert them to codes the XML parser can understand.
You could have a look at the unicodedata package, especially the normalize method.
I haven't used it myself, so I can't tell you all that much, but you could ask again here on SO if you decide you're going to convert and keep that data.
>>> import unicodedata
>>> unicodedata.normalize("NFKD" , u"ไภเฟล &")
u'a\u03001\u201ea\u0300 \u0327 a\u03001\u20aca\u0300 \u0327Y\u0308a\u0300 \u0327\xa5 &'

It looks like you're dealing with data which are saved with some kind of encoding "as if" they were ASCII. XML file should normally be UTF8, and SAX (the underlying parser used by minidom) should handle that, so it looks like something's wrong in that part of the processing chain. Instead of focusing on "cleaning up" I'd first try to make sure the encoding is correct and correctly recognized. Maybe a broken XML directive? Can you edit your Q to show the first few lines of the file, especially the <?xml ... directive at the very start?

I'd throw out all non-ASCII characters which can be identified by having the 8th bit (0x80) set (128 .. 255 respectively 0x80 .. 0xff).
You could read in the file into a Python string named old_str
Then perform a filter call in conjunction with a lambda statement:
new_str = filter(lambda x: x in string.ascii_letters, old_str)
Parse new_str
Many ways exist to accomplish stripping non-ASCII characters from a string.
This question might be related: How to check if a string in Python is in ASCII?