Re: Idenfity numbers in variables

[Lie Ryan]

On Mon, 20 Oct 2008 13:16:48 +0200, Alfons Nonell-Canals wrote:

Hello,
I have a trouble and I don't know how to solve it. I am working with
molecules and each molecule has a number of atoms. I obtain each atom
spliting the molecule.
>
Ok. It is fine and I have no problem with it.
>
The problem is when I have to work with these atoms. These atoms usually
are only a letter but, sometimes it can also contain one o more numbers.
If they contein a number I have to manipulate them separately.
>
If the number was allways the same I know how to identify them, for
example, 1:
>
atom = 'C1'
>
if '1' in atom:
print 'kk'
>
But, how can I do to identify in '1' all possibilities from 1-9, I
tried:
>
if '[1-9]', \d,...
>

That's the job of regular expression: 'import re'

numbered_atom = re.compile('[A-Z][a-z]?[0-9]+')
if numbered_atom.m atch('C10'):
# this is a numbered atom
if numbered_atom.m atch('C'):
# this WON'T match

read more about regular expression on the web (hint: python share the
same re syntax with many other languages, php, javascript, grep, etc)

[Duncan Booth]

Re: Idenfity numbers in variables

Lie Ryan <lie.1296@gmail .comwrote:

That's the job of regular expression: 'import re'
>
numbered_atom = re.compile('[A-Z][a-z]?[0-9]+')
if numbered_atom.m atch('C10'):
# this is a numbered atom
if numbered_atom.m atch('C'):
# this WON'T match
>
read more about regular expression on the web (hint: python share the
same re syntax with many other languages, php, javascript, grep, etc)
>

Or simply:

if atom[-1].isdigit():
# this is a numbered atom
else:
# this isn't