Need help vectorizing code
I have some code that I need help vectorizing. I want to convert the following to vector form, how can I? I want to get rid of the inner loop - apparently, it's possible to do so. X is an NxD matrix. y is a 1xD vector. def foo(X, y, mylambda, N, D, epsilon): ... for j in xrange(D): aj = 0 cj = 0 for i in xrange(N): aj += 2 * (X[i,j] ** 2) cj += 2 * (X[i,j] * (y[i] - w.transpose()*X[i].transpose() + w[j]*X[i,j])) ... If I call numpy.vectorize() on the function, it throws an error at runtime. Thanks -- https://mail.python.org/mailman/listinfo/python-list
Re: Need help vectorizing code
I didn't paste the whole function, note the ... before and after. I do use the values. I want to get rid of one of the loops so that the computation becomes O(D). Assume vectors a and c should get populated during the compute, each being 1xD. Thanks On Saturday, January 18, 2014 12:51:25 PM UTC-8, Kevin K wrote: > I have some code that I need help vectorizing. > > I want to convert the following to vector form, how can I? I want to get rid > of the inner loop - apparently, it's possible to do so. > > X is an NxD matrix. y is a 1xD vector. > > > > def foo(X, y, mylambda, N, D, epsilon): > > ... > > for j in xrange(D): > > aj = 0 > > cj = 0 > > for i in xrange(N): > > aj += 2 * (X[i,j] ** 2) > > cj += 2 * (X[i,j] * (y[i] - w.transpose()*X[i].transpose() + > w[j]*X[i,j])) > > > > ... > > > > If I call numpy.vectorize() on the function, it throws an error at runtime. > > > > Thanks -- https://mail.python.org/mailman/listinfo/python-list
File IO Issues, help :(
Hey everyone, I'm new to python and am trying to do a little project
with it. I'm running into problems writing over a file. I read from
the file and loop through for a specfic case in which I change
something. After I open and give it opening options (w, r, etc) one of
two things happens: either the file gets truncated and my writing
never takes place (or it seems it doesnt) or everything is appended to
the file and I have a double of what I started with, its never just
the updated file. Can someone shed some light on this for me?? Code
below:
jsfile = open("../timeline.js", "r+")
jscontent = jsfile.readlines()
jsfile.truncate()
for line in jscontent:
if re.search('var d =', line):
line = "var d = \""+mint['1'].ascdate()+"\"\n"
print line
jsfile.write(line)
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Re: File IO Issues, help :(
On Apr 29, 12:38 am, "Eric Wertman" <[EMAIL PROTECTED]> wrote:
> chuck in a jsfile.close(). The buffer isn't flushing with what you
> are doing now. jsfile.flush() might work... not sure. Closing and
> re-opening the file for sure will help though.
>
Yeah sorry I forgot to include the close() in the quote but its there.
In fact I moved it up a bit and still no luck heres the new code:
jsfile = open("../timeline.js", "r+")
jscontent = jsfile.readlines()
jsfile.truncate()
for line in jscontent:
if re.search('var d =', line):
line = "var d = \""+mint['1'].ascdate()+"\"\n"
print line
jsfile.write(line)
jsfile.close()
I tried this can got the same result...??
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Re: File IO Issues, help :(
On Apr 29, 12:55 am, Peter Otten <[EMAIL PROTECTED]> wrote:
> Kevin K wrote:
> > On Apr 29, 12:38 am, "Eric Wertman" <[EMAIL PROTECTED]> wrote:
> >> chuck in a jsfile.close(). The buffer isn't flushing with what you
> >> are doing now. jsfile.flush() might work... not sure. Closing and
> >> re-opening the file for sure will help though.
>
> > Yeah sorry I forgot to include the close() in the quote but its there.
> > In fact I moved it up a bit and still no luck heres the new code:
>
> > jsfile = open("../timeline.js", "r+")
> > jscontent = jsfile.readlines()
> > jsfile.truncate()
>
> > for line in jscontent:
> > if re.search('var d =', line):
> > line = "var d = \""+mint['1'].ascdate()+"\"\n"
> > print line
> > jsfile.write(line)
> > jsfile.close()
>
> > I tried this can got the same result...??
>
> """
> truncate(...)
> truncate([size]) -> None. Truncate the file to at most size bytes.
>
> Size defaults to the current file position, as returned by tell().
> """
>
> After the readlines() call the current file position is at the end of the
> file. Try jsfile.truncate(0).
>
> Also note that readlines() reads the whole file into memory. For large files
> it would therefore be better to write to a new file and rename it
> afterwards.
>
> Peter
Thanks Peter that seemed to be most of the problem, however I now have
a bunch of null characters in the file. Could it be an unwanted line
in the list that im writing?
Thanks,
Kevin
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Re: File IO Issues, help :(
On Apr 29, 1:07 am, Kevin K <[EMAIL PROTECTED]> wrote:
> On Apr 29, 12:55 am, Peter Otten <[EMAIL PROTECTED]> wrote:
>
>
>
> > Kevin K wrote:
> > > On Apr 29, 12:38 am, "Eric Wertman" <[EMAIL PROTECTED]> wrote:
> > >> chuck in a jsfile.close(). The buffer isn't flushing with what you
> > >> are doing now. jsfile.flush() might work... not sure. Closing and
> > >> re-opening the file for sure will help though.
>
> > > Yeah sorry I forgot to include the close() in the quote but its there.
> > > In fact I moved it up a bit and still no luck heres the new code:
>
> > > jsfile = open("../timeline.js", "r+")
> > > jscontent = jsfile.readlines()
> > > jsfile.truncate()
>
> > > for line in jscontent:
> > > if re.search('var d =', line):
> > > line = "var d = \""+mint['1'].ascdate()+"\"\n"
> > > print line
> > > jsfile.write(line)
> > > jsfile.close()
>
> > > I tried this can got the same result...??
>
> > """
> > truncate(...)
> > truncate([size]) -> None. Truncate the file to at most size bytes.
>
> > Size defaults to the current file position, as returned by tell().
> > """
>
> > After the readlines() call the current file position is at the end of the
> > file. Try jsfile.truncate(0).
>
> > Also note that readlines() reads the whole file into memory. For large files
> > it would therefore be better to write to a new file and rename it
> > afterwards.
>
> > Peter
>
> Thanks Peter that seemed to be most of the problem, however I now have
> a bunch of null characters in the file. Could it be an unwanted line
> in the list that im writing?
>
> Thanks,
> Kevin
Awesome that seems to work fine! Thanks a lot for your help guys!
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