[Tutor] Pickling files in Python
Hi all
I am new to programming and on a very steep curve. I am using Python 3 to
learn and I am having trouble understanding exactly what pickling is. I have
written a program that asks for a URL and then writes the source code from the
URL to a file, then pickles the file I just created. I am not sure why I pickle
something as opposed to just saving it as a normal file?
I saved the url source code file as a .txt and also the pickled file as .txt. I
am not sure of the filetype I should save a pickled file as.When I look at the
files (the saved source file and the pickled file) they look the same. I am
viewing them in notepad on the Mac.
Many thanksJoe
Pickle an
object- Puzzle 5 # Joe Batt 18 Nov 2011 -
http://www.pythonchallenge.com/pc/def/peak.html###
import pickleimport urllib
def geturlfile(urlfile):#gets the user URL from main opens it and saves it to
var fileurlfrom urllib.request import urlopen
fileurl=urlopen(urlfile)#opens the file on computer and writes the var fileurl
to ithtml_file=open('///Users/joebatt/Desktop/python/puzzle5.txt','w')
for line in fileurl.readlines():linestring=line.decode(utf-8)
#ensures written in string not bytehtml_file.write(linestring)
html_file.close() #closes the puzzle file#just prints file to check its correct
html_file=open('///Users/joebatt/Desktop/python/puzzle5.txt','r')
filecontents=html_file.read()html_file.close()print (filecontents)
print (type(filecontents))
#pickles the file filecontents containing the url file
pickledfile=open('///Users/joebatt/Desktop/python/pickledpuzzle5.txt','wb')
pickle.dump(filecontents,pickledfile)pickledfile.close() return ()
# Main programurlfile=input('Please input the URL ')geturlfile(urlfile)
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[Tutor] Further pickle problem :0(
Hi all again
Thank you to those that have helped me previously with this problem it is
appreciated.
Thanks to Walter I have actually found the pickle file that I am trying to
restore to a variable however I am getting the following error
Traceback (most recent call last): File
/Users/joebatt/Desktop/python/pickling puzzle 5.py, line 39, in module
a=pickle.load(file) File
/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/encodings/ascii.py,
line 26, in decodereturn codecs.ascii_decode(input,
self.errors)[0]UnicodeDecodeError: 'ascii' codec can't decode byte 0xd1 in
position 8: ordinal not in range(128)
The simple program I am using to 'depickle' is
file=open('///Users/joebatt/Desktop/banner.p.webarchive','r')a=pickle.load(file)file.close()print
(a)
I am using Python 3 and working through the Python Challenges on
www.pythonchallenge.com, the site is a few years old and I was thinking that
possibly it is based around Python 2.x ??? If thats the case is the error due
to me using 3 as opposed to 2.x
Many thanksJoe___
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[Tutor] Stacks and Stack underflow/Stack overflow
Hi All
Could some kind soul please explain why you get a stack underflow and a stack
overflow.
I am getting the following error in Python 3
Traceback (most recent call last): File
/Users/joebatt/Desktop/python/pickling puzzle 5.py, line 39, in module
a=pickle.load(file)_pickle.UnpicklingError: unpickling stack underflow
when I am running the following
import
picklefile=open('///Users/joebatt/Desktop/banner.p.webarchive','rb')a=pickle.load(file)file.close()print
(a)
Now I am very much a learner so please correct and explain my misunderstanding.
I am visualising my program as taking the 'banner.p.webarchive' and and pushing
it onto the stack byte by byte until it reaches the end of the file i.e. A B C
--- push C then B then A
A B C --- A B C
Then the program pops the stack C does what it needs to do to unpickle it then
pops B does what it needs to unpickle then A.
A -C B ABC
My understanding is that the stack underflow means that it is trying to pop
from the top of the stack and there is nothing to pop i.e. it is empty. Why
though if the stack has been loaded with the file 'banner.p' in my program does
it say there is nothing to pop and thus a stack underflow?
Also my understanding of the stack overflow is that the stack itself is a
finite size and when it has tried to push the file to the stack it didn't fit
because it was too big, i.e. in my example if the stack was only big enough for
2 letters and I tried to push ABC it would give a stack overflow because I was
trying to push 3. How would I deal with this? Can I make the stack bigger or a
way to just push A B pop AB then push C and pop it.
Thank you guys Im sorry for probably what are very silly basic questions.
Joe ___
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[Tutor] In a pickle over pickles….Python 3
Hi All,Sorry to trouble you all again with more nooby problems! Only been
programming a week so still all a haze especially since self taught…..
I am opening a url and saving it to a file on my computer, then I am trying to
pickle it. I have written the url file to a file on my computer then opened it
and assigned the contents to a var 'filecontents' and tried to pickle it it is
giving the error:
Traceback (most recent call last): File
/Users/joebatt/Desktop/python/pickling puzzle 5.py, line 39, in module
geturlfile(urlfile) File /Users/joebatt/Desktop/python/pickling puzzle 5.py,
line 28, in geturlfilepickle.dump(filecontents,pickledfile)TypeError: must
be str, not bytes
Yet I tested the variable filecontents using print (type(file contents)) and
it is saying that it is a str yet the error seems to indicate it is a byte, can
anyone point me in the right direction please?
(I know my coding is very untidy and verbose, sorry I am very new and at the
moment I have to think in baby steps with little knowledge!)
Joe
Pickle an
object- ###
import pickleimport urllib
def geturlfile(urlfile):#gets the user URL from main opens it and saves it to
var fileurlfrom urllib.request import urlopen
fileurl=urlopen(urlfile)#opens the file on computer and writes the var fileurl
to ithtml_file=open('///Users/joebatt/Desktop/python/puzzle5.txt','w')
for line in fileurl.readlines():linestring=line.decode(utf-8)
#ensures written in string not bytehtml_file.write(linestring)
html_file.close() #closes the puzzle file#just prints file to check its correct
html_file=open('///Users/joebatt/Desktop/python/puzzle5.txt','r')
filecontents=html_file.read()html_file.close()print (filecontents)
print (type(filecontents))
#pickles the file filecontents containing the url file
pickledfile=open('///Users/joebatt/Desktop/python/pickledpuzzle5.txt','w')
pickle.dump(filecontents,pickledfile)pickledfile.close()
return ()
# Main programurlfile=input('Please input the URL ')geturlfile(urlfile)
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[Tutor] Printing with no newline :(
I am learning Python 3 and programming and am very new so please bear with me… I am writing a program to pull out specific characters in a sequence and then print then out. So far so good however when the characters are printed out they pint on separate lines as opposed to what I want, all on the same line. I have tried \n and just , in the pint statement i.e. print(letterGroup[4],) and print(letterGroup[4]\n) and even print(letterGroup[4],/n)…….. Can anyone help and explain please….Thank you for line in file:m = re.search(regexp, line)if m: letterGroup=m.group(0)print(letterGroup[4]) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Help with re in Python 3
Hi all,Still trying with Python and programming in general….
I am trying to get a grip with re. I am writing a program to open a text file
and scan it for exactly 3 uppercase letters in a row followed by a lowercase
followed by exactly 3 uppercase letters. ( i.e. oooXXXoXXXooo )If possible
could you explain why I am getting EOL while scanning string literal when I
try running the following program in Python 3.
My program:
import
reregexp=re.compile(r[a-z]r[A-Z]r[A-Z]r[A-Z]r[a-z]r[A-Z]r[A-Z]r[A-Z]r[a-z])
file=('///Users/joebatt/Desktop/python3.txt','r')for line in
file.readlines():if regexp.search(line):print(Found value 3 caps
followed by lower case followed by 3 caps)file.close()
If possible could you explain why I am getting EOL while scanning string
literal when I try running my program in Python 3.
Thanks for your help
Joe
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[Tutor] A total newbie…sorry
I am just starting to try to learn Python on IDLE on a Mac running Python 3.2.2 (v3.2.2:137e45f15c0b, Sep 3 2011, 17:28:59) and I have come unstuck at the very beginning I tried print HelloSyntaxError: invalid syntax print 'Hello'SyntaxError: invalid syntax print HelloSyntaxError: invalid syntax And as you can see its just saying invalid syntax yet if I run Python in the terminal using the same syntax it works Python 2.7.1 (r271:86832, Jun 16 2011, 16:59:05) [GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwinType help, copyright, credits or license for more information. print HelloHello I can see its a different version but what is the problem? Many thanks and sorry for the VERY basic question :( Joe ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
