Hello!

I'm trying to find a way to print out a long string (>400 characters no
spaces, tabs or newlines) to a line width of 60 characters. So after every
60 characters a newline would start. Is it possible to transform the
string to set the linewidth?

for example for a linewidth of 2:

.... {do something to str to set width to 2} ...

He
LL
oW
or
ld
!

i know in Perl this works:
my $str = "HelloWorld!" ;
$str =~ s/.{2}/$&\n/g ; #at {2} you can then specify the desired width
print $ str ;

But how to do it in Python?
An option in the print statement would also be fine.
Something like: print "%{2}s" %(str)

Of course i could do it in a for loop and print 60 characters, print a \n,
print the next 60 characters, print a \n ...
But i imagine there will be a more efficient way.

Thanks
Eddie

elukkien@cmbi.ru.nl wrote:

I'm trying to find a way to print out a long string (>400 characters
no spaces, tabs or newlines) to a line width of 60 characters. So
after every 60 characters a newline would start. Is it possible to
transform the string to set the linewidth?
>
for example for a linewidth of 2:
>

>
... {do something to str to set width to 2} ...
>

He
LL
oW
or
ld
!

He
ll
oW
or
ld

Of course if your assertion that the string contains no spaces, tabs or
newlines turns out to be incorrect this may not do what you wanted.

--
Duncan Booth http://kupuguy.blogspot.com

>>>import textwrap

He
ll
oW
or
ld
>
Of course if your assertion that the string contains no spaces, tabs or
newlines turns out to be incorrect this may not do what you wanted.

Thanks, i just found this myself and it works fine, but very slow...
The script without the wrapping takes 30 seconds, with wrapping 30
minutes. Is there not a more efficient way?
The perl syntax i posted is much faster.

elukkien@cmbi.ru.nl wrote:

Thanks, i just found this myself and it works fine, but very slow...
The script without the wrapping takes 30 seconds, with wrapping 30
minutes. Is there not a more efficient way?

sounds like you're wrapping a few million long strings, not just one...

here are two approaches that are about 10x faster than textwrap:

re.findall('..', my_string)

or

[my_string[i:i+2] for i in xrange(0, len(my_string), 2]

the above gives you lists of string fragments; you can either join them
before printing; e.g.

print "'\n'.join(re.findall('..', my_string))

or use writelines directly:

sys.stdout.writelines(s + "\n" for s in re.findall('..', my_string))

Python's re.sub isn't as efficient as Perl's corresponding function, so
a direct translation of your Perl code to

re.sub('(..)', r'\1\n', my_string)

or, faster (!):

re.sub('(..)', lambda m: m.group() + "\n", my_string)

is not as fast as the above solutions.

</F>

On Aug 13, 10:13 pm, elukk...@cmbi.ru.nl wrote:

>

>
Thanks, i just found this myself and it works fine, but very slow...
The script without the wrapping takes 30 seconds, with wrapping 30
minutes. Is there not a more efficient way?
The perl syntax i posted is much faster.

.... return ''.join(s[x:x+w] + '\n' for x in xrange(0, len(s), w))
....

'He\nll\noW\nor\nld\n'

'Hel\nloW\norl\nd\n'

'HelloWorld\n'