splitting a string into 2 new strings

[Mark Light]

Hi,
I have a string e.g. 'C6 H12 O6' that I wish to split up to give 2
strings
'C H O' and '6 12 6'. I have played with string.split() and the re module -
but can't quite get there.

Any help would be greatly appreciated.

Thanks,

Mark.

[trp]

Re: splitting a string into 2 new strings

Mark Light wrote:
[color=blue]
> Hi,
> I have a string e.g. 'C6 H12 O6' that I wish to split up to give 2
> strings
> 'C H O' and '6 12 6'. I have played with string.split() and the re module
> - but can't quite get there.
>
> Any help would be greatly appreciated.
>
> Thanks,
>
> Mark.[/color]

I'm, assuming that these are chemical compounds, so you're not limited to
one-character symbols.

Here's how I'd do it

import re

re_pat = re.compile('([A-Z]+)(\d+)')
text = 'C6 H12 O6'

# find each component, returns list of tuples (e.g. [('C', '6'), ...]
component = re_pat.findall( text)

#split into separate lists
symbols, counts = zip(*component)

# create the strings
symbols = ' '.join(symbols)
counts = ' '.join(counts)

--Andy

[Mark Light]

Re: splitting a string into 2 new strings

that works great - many thanks.

"trp" <trp@smyrncable .net> wrote in message
news:vg5jjqcc8d 2r1f@corp.super news.com...[color=blue]
> Mark Light wrote:
>[color=green]
> > Hi,
> > I have a string e.g. 'C6 H12 O6' that I wish to split up to give 2
> > strings
> > 'C H O' and '6 12 6'. I have played with string.split() and the re[/color][/color]
module[color=blue][color=green]
> > - but can't quite get there.
> >
> > Any help would be greatly appreciated.
> >
> > Thanks,
> >
> > Mark.[/color]
>
> I'm, assuming that these are chemical compounds, so you're not limited to
> one-character symbols.
>
> Here's how I'd do it
>
> import re
>
> re_pat = re.compile('([A-Z]+)(\d+)')
> text = 'C6 H12 O6'
>
> # find each component, returns list of tuples (e.g. [('C', '6'), ...]
> component = re_pat.findall( text)
>
> #split into separate lists
> symbols, counts = zip(*component)
>
> # create the strings
> symbols = ' '.join(symbols)
> counts = ' '.join(counts)
>
> --Andy
>
>
>
>
>[/color]

[P@draigBrady.com]

Re: splitting a string into 2 new strings

Mark Light wrote:[color=blue]
> Hi,
> I have a string e.g. 'C6 H12 O6' that I wish to split up to give 2
> strings
> 'C H O' and '6 12 6'. I have played with string.split() and the re module -
> but can't quite get there.
>
> Any help would be greatly appreciated.[/color]

import re

molecule_re = re.compile("(.+ ?)([0-9]+)")
def processMolecule (molecule):
elements=[]
numbers=[]

for item in molecule.split( ):
element, number = molecule_re.fin dall(item)[0]
elements.append (element)
numbers.append( number)

elements = ' '.join(elements )
numbers = ' '.join(numbers)

return (elements, numbers)

print processMolecule ('C6 H12 O6')

[Andrew Dalke]

Re: splitting a string into 2 new strings

trp:[color=blue]
> I'm, assuming that these are chemical compounds, so you're not limited to
> one-character symbols.[/color]

The problem is underspecified. Usually 2-character (or 3-character for some
elements with high atomic number, and not assuming the newer IUPAC names
like "Dubnium", which was also called Unnilpentium (Unp) or, depending on
your political persuasion, Joliotium (Jl) or Hahnium (Ha)) have the first
letter
capitalized and the rest in lower case.
[color=blue]
> re_pat = re.compile('([A-Z]+)(\d+)')[/color]

So this should be written ([A-Z][A-Za-z]*)(\d+), where I explicitly allow
both lower and upper case trailing letters to be more accepting. (In some
systems, "CU" is "1 carbon + 1 uranium" and in others it's an alternate way
to
write "1 copper". Though I suspect it's not allowed in the OP's problem.)

Andrew
dalke@dalkescie ntific.com

[Andrew Dalke]

Re: splitting a string into 2 new strings

Anton Vredegoor:[color=blue]
> The issue seems to be resolved already, but I haven't seen the split
> and strip combination:
>
> from string import letters,digits[/color]

Use "ascii_lett ers" instead of "letters". The latter is based on the locale
so
might not work on some machines where "C" (or rather, byte 67) isn't
a letter in the local alphabet.

Andrew
dalke@dalkescie ntific.com

[Andrew Dalke]

Re: splitting a string into 2 new strings

trp:[color=blue]
> I'm, assuming that these are chemical compounds, so you're not limited to
> one-character symbols.[/color]

The problem is underspecified. Usually 2-character (or 3-character for some
elements with high atomic number, and not assuming the newer IUPAC names
like "Dubnium", which was also called Unnilpentium (Unp) or, depending on
your political persuasion, Joliotium (Jl) or Hahnium (Ha)) have the first
letter
capitalized and the rest in lower case.
[color=blue]
> re_pat = re.compile('([A-Z]+)(\d+)')[/color]

So this should be written ([A-Z][A-Za-z]*)(\d+), where I explicitly allow
both lower and upper case trailing letters to be more accepting. (In some
systems, "CU" is "1 carbon + 1 uranium" and in others it's an alternate way
to
write "1 copper". Though I suspect it's not allowed in the OP's problem.)

Andrew
dalke@dalkescie ntific.com

[Andrew Dalke]

Re: splitting a string into 2 new strings

Anton Vredegoor:[color=blue]
> The issue seems to be resolved already, but I haven't seen the split
> and strip combination:
>
> from string import letters,digits[/color]

Use "ascii_lett ers" instead of "letters". The latter is based on the locale
so
might not work on some machines where "C" (or rather, byte 67) isn't
a letter in the local alphabet.

Andrew
dalke@dalkescie ntific.com