On Sep 20, 5:46 pm, Paul Hankin <[EMAIL PROTECTED]> wrote:
> On Sep 20, 10:59 pm, Python Maniac <[EMAIL PROTECTED]> wrote:
>
> > I am new to Python however I would like some feedback from those who
> > know more about Python than I do at this time.
>
> > def scrambleLine(line):
> > s = ''
> > for c in line:
> > s += chr(ord(c) | 0x80)
> > return s
>
> > def descrambleLine(line):
> > s = ''
> > for c in line:
> > s += chr(ord(c) & 0x7f)
> > return s
> > ...
>
> Well, scrambleLine will remove line-endings, so when you're
> descrambling
> you'll be processing the entire file at once. This is particularly bad
> because of the way your functions work, adding a character at a time
> to
> s.
>
> Probably your easiest bet is to iterate over the file using read(N)
> for some small N rather than doing a line at a time. Something like:
>
> process_bytes = (descrambleLine, scrambleLine)[action]
> while 1:
> r = f.read(16)
> if not r: break
> ff.write(process_bytes(r))
>
> In general, rather than building strings by starting with an empty
> string and repeatedly adding to it, you should use ''.join(...)
>
> For instance...
> def descrambleLine(line):
> return ''.join(chr(ord(c) & 0x7f) for c in line)
>
> def scrambleLine(line):
> return ''.join(chr(ord(c) | 0x80) for c in line)
>
> It's less code, more readable and faster!
I would have thought that also from what I've heard here.
def scrambleLine(line):
s = ''
for c in line:
s += chr(ord(c) | 0x80)
return s
def scrambleLine1(line):
return ''.join([chr(ord(c) | 0x80) for c in line])
if __name__=='__main__':
from timeit import Timer
t = Timer("scrambleLine('abcdefghijklmnopqrstuvwxyz')", "from
__main__ import scrambleLine")
print t.timeit()
## scrambleLine
## 13.0013366039
## 12.9461998318
##
## scrambleLine1
## 14.4514098748
## 14.3594400695
How come it's not? Then I noticed you don't have brackets in
the join statement. So I tried without them and got
## 17.6010847978
## 17.6111472418
Am I doing something wrong?
>
> --
> Paul Hankin
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