Equations with Regular Expressions

[Aktay SW]

Equations with Regular ExpressionsHi,

here is a piece of code that does the conversion:


*************************************

import re                    # import the regular expressions module

s='2x^3-2x^2+15'    # set up the original string
s1=s                        # make a copy of the original string. it will be
modified for searching purposes
s2=''                        # create an empty resulting string

match=re.search('[0-9]x\^[0-9]+',s1)    # search the string s1 for the first
time for: one digit followed by 'x^' followed by one or more digits

while match:                            # loop as long as there is a match

    begin,end = match.span()    # get beginning and ending character
positions of matching portion

    if begin > 0:                       # if the matching portion does not
begin at the first character position you have to copy to the resulting
string
        s2=s2+s1[:begin]                # the characters from the beginning
of the string up to the first matching character


s2=s2+s1[begin:begin+1]+'*('+s1[begin+1:begin+2]+'**'+s1[begin+3:end]+')'
                                        # paste the characters '*(', '**',
')' into the matching portion and add it to the resulting string

    s1=s1[end:]                         # shorten string s1 by the
characters up the first character after the matching portion

    match=re.search('[0-9]x\^[0-9]*',s1)# do the search again and go through
the loop if there was a match, else you're done with the loop

s2=s2+s1            # add any leftover characters to the resulting string
print s             # print original string
print s2            # print conversion result

*************************************

I hope this helps you

regards

Ruhi Aktay
software

"Alves, Carlos Alberto - Coelce" <calves at coelce.com.br> schrieb im
Newsbeitrag news:mailman.1014805905.18241.python-list at python.org...
Hi everybody,
Could someone of you give me and example of how can I translate
'2x^3-2x^2+15' into '2*(x**3)-2*(x**2)+15' using regular expressions.
Carlos Alberto
COELCE/DPRON-Departamento de Projetos e Obras Norte
Fone: 677- 2228
e-mail: calves at coelce.com.br
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