Re: [Tutor] problems pickling functions
Arild B. Næss wrote: > I haven't found out how to change the working directory in IDLE, > though – and for some reason it seems to be a different one this > session from the last one. Does anyone know? > (I use a mac by the way.) take a look at os.chdir() This changes the interpreter's working dir (and thus whatever you're writing into the prompt in IDLE) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] problems pickling functions
Den 8. des. 2006 kl. 15.43 skrev Kent Johnson: > Arild B. Næss wrote: >> Den 8. des. 2006 kl. 14.05 skrev Kent Johnson: >>> Why do you need to pickle the function? Is it created >>> dynamically? Can you just pickle the data? >>> >>> Kent >>> >> Thanks. >> I guess it's not absolutely necessary to pickle the function. I >> tried to do this because I wanted to use the function in the >> interpreter without having to write it in there line by line. >> I'm used to working in R and Matlab, where you often run scripts >> from the active interpreter. In that way you can actually >> examine the data a script generates, instead of having the script >> print it to screen or file. >> I'm having trouble getting used to python like this because I get >> trouble trying to paste in several lines at once from emacs, and >> I haven't found a way to run scripts in the interpreter. > > Two suggestions: > - Use an editor / IDE that allows you to run Python scripts. IDLE > will do this. I think emacs has good support for Python too but > someone who uses emacs will have to help you with that one. > > - Save your function in a module and import the module from the > interpreter. Then you can run the function in the interpreter. > > For example if you have funcs.py in the working directory and it > contains a function > def doItAll(): > pass > > then in the interpreter you can type > >>> import funcs > >>> funcs.doItAll() > > to run the function. > > If you change the function in an external editor you have to reload > it in the interpreter to get the revised version: > >>> reload(funcs) Thanks. That worked. I haven't found out how to change the working directory in IDLE, though – and for some reason it seems to be a different one this session from the last one. Does anyone know? (I use a mac by the way.) > > PS Please reply to the list, not to me directly. Sorry about that. I didn't realize my client picked your adress and not the list's when I clicked reply. My mistake. regards, Arild Næss ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] problems pickling functions
Arild B. Næss wrote: > Den 8. des. 2006 kl. 14.05 skrev Kent Johnson: >> Why do you need to pickle the function? Is it created dynamically? >> Can you just pickle the data? >> >> Kent >> > > Thanks. > > I guess it's not absolutely necessary to pickle the function. I tried > to do this because I wanted to use the function in the interpreter > without having to write it in there line by line. > > I'm used to working in R and Matlab, where you often run scripts from > the active interpreter. In that way you can actually examine the > data a script generates, instead of having the script print it to > screen or file. > > I'm having trouble getting used to python like this because I get > trouble trying to paste in several lines at once from emacs, and I > haven't found a way to run scripts in the interpreter. Two suggestions: - Use an editor / IDE that allows you to run Python scripts. IDLE will do this. I think emacs has good support for Python too but someone who uses emacs will have to help you with that one. - Save your function in a module and import the module from the interpreter. Then you can run the function in the interpreter. For example if you have funcs.py in the working directory and it contains a function def doItAll(): pass then in the interpreter you can type >>> import funcs >>> funcs.doItAll() to run the function. If you change the function in an external editor you have to reload it in the interpreter to get the revised version: >>> reload(funcs) Kent PS Please reply to the list, not to me directly. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] problems pickling functions
Arild B. Næss wrote:
> Hi,
>
> I'm writing a program for tagging which requires a long time to
> calculate the parameters. I have therefore tried to write a long
> program that pickles all the data, and pickles a function that uses
> these parameters to tag an input sentence.
>
> But I'm having trouble with loading the function. The odd thing is
> that it works fine in the interpreter to pickle and load a function:
>
> >>> import pickle
> >>> def simple():
> ... print "This works"
> ...
> >>> f=open("simple.txt","w")
> >>> pickle.dump(simple,f)
> >>> f.close()
> >>> s()
> Traceback (most recent call last):
>File "", line 1, in
> NameError: name 's' is not defined
> >>> f=open("simple.txt","r")
> >>> s=pickle.load(f)
> >>> s()
> This works
>
> However when I try to do this with the script simple.py (with the
> exact same commands as above) it doesn't work:
>
> $ cat simple.py
>
> import pickle
>
> def simple():
> print "This works"
>
> f = open("simple.txt","w")
> pickle.dump(simple,f)
> f.close()
>
> $ python simple.py
> $ python
> Python 2.5 (r25:51918, Sep 19 2006, 08:49:13)
> [GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import pickle
> >>> f2 = open("simple.txt","r")
> >>> s
> Traceback (most recent call last):
>File "", line 1, in
> NameError: name 's' is not defined
> >>> s = pickle.load(f2)
> Traceback (most recent call last):
>File "", line 1, in
>File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
> python2.5/pickle.py", line 1370, in load
> return Unpickler(file).load()
>File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
> python2.5/pickle.py", line 858, in load
> dispatch[key](self)
>File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
> python2.5/pickle.py", line 1090, in load_global
> klass = self.find_class(module, name)
>File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
> python2.5/pickle.py", line 1126, in find_class
> klass = getattr(mod, name)
> AttributeError: 'module' object has no attribute 'simple'
> >>>
>
> I don't get this error message, and I'm annoyed – because I'm used to
> that things that work in the interpreter also work when written as a
> program.
From the docs for pickle (13.1.4 What can be pickled and unpickled?):
"Note that functions (built-in and user-defined) are pickled by ``fully
qualified'' name reference, not by value. This means that only the
function name is pickled, along with the name of module the function is
defined in. Neither the function's code, nor any of its function
attributes are pickled. Thus the defining module must be importable in
the unpickling environment, and the module must contain the named
object, otherwise an exception will be raised."
Your code works from the interpreter because 'simple' is still defined.
If you 'del simple' before you unpickle I think you will get the same
error as you get in the script.
Searching comp.lang.python for 'pickle function' yields a few possible
workarounds but they are messy.
Why do you need to pickle the function? Is it created dynamically? Can
you just pickle the data?
Kent
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[Tutor] problems pickling functions
Hi,
I'm writing a program for tagging which requires a long time to
calculate the parameters. I have therefore tried to write a long
program that pickles all the data, and pickles a function that uses
these parameters to tag an input sentence.
But I'm having trouble with loading the function. The odd thing is
that it works fine in the interpreter to pickle and load a function:
>>> import pickle
>>> def simple():
... print "This works"
...
>>> f=open("simple.txt","w")
>>> pickle.dump(simple,f)
>>> f.close()
>>> s()
Traceback (most recent call last):
File "", line 1, in
NameError: name 's' is not defined
>>> f=open("simple.txt","r")
>>> s=pickle.load(f)
>>> s()
This works
However when I try to do this with the script simple.py (with the
exact same commands as above) it doesn't work:
$ cat simple.py
import pickle
def simple():
print "This works"
f = open("simple.txt","w")
pickle.dump(simple,f)
f.close()
$ python simple.py
$ python
Python 2.5 (r25:51918, Sep 19 2006, 08:49:13)
[GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> f2 = open("simple.txt","r")
>>> s
Traceback (most recent call last):
File "", line 1, in
NameError: name 's' is not defined
>>> s = pickle.load(f2)
Traceback (most recent call last):
File "", line 1, in
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/pickle.py", line 1370, in load
return Unpickler(file).load()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/pickle.py", line 858, in load
dispatch[key](self)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/pickle.py", line 1090, in load_global
klass = self.find_class(module, name)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/pickle.py", line 1126, in find_class
klass = getattr(mod, name)
AttributeError: 'module' object has no attribute 'simple'
>>>
I don't get this error message, and I'm annoyed – because I'm used to
that things that work in the interpreter also work when written as a
program.
Can anyone help?
regards,
Arild Næss
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