Dnia Sun, 10 Aug 2008 15:52:37 +0200, WP napisa�(a):
Hi,
> import re
>
> def calculate_sum_1(str):
^^^
this word is reserved, better use some other name
> for c in str:
> if c.isdigit() == False and c != ' ':
> # That we assign to the variable we're looping over worries
> me...
> str = str.replace(c, ' ')
It's good that it worries you. AFAIR python behavior when assigning to
a variable that is used in for loop is undefined, so you can't count
on it. Better introduce second variable.
>
> mylist = str.split()
>
> print "(for loop version) mylist after replace() and split() = ",
> mylist
>
> sum = 0
>
> for item in mylist:
> sum += long(item)
You could use list comprehensions and sum function in here.
> def calculate_sum_2(str):
> #print "In replace_nondigits_2(), str = ", str
> p = re.compile('[^0-9]')
or: p = re.compile('\d+')
'\d+' is for one or more digits
> mylist = p.split(str)
You don't have to split this string. Just search through it.
Findall method seems appropriate.
A bit more pythonic approaches to both of your functions:
=======================
import re
a="123xx,22! p1"
# Note that 'string' isn't the best name too. It may be shadowed by
# or shadow 'string' module if it's imported.
def calculate_sum_1(string):
result = ''
for i in string:
if i.isdigit():
result += i
else:
result += ' '
return sum([int(i) for i in result.split()])
def calculate_sum_2(string):
pat = re.compile('\d+')
digits = [int(i) for i in re.findall(pat, string)]
return sum(digits)
print calculate_sum_1(a)
print calculate_sum_2(a)
===========================
--
Regards,
Wojtek Walczak,
http://www.stud.umk.pl/~wojtekwa/
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