How to find the parentheses and calculate the percentage of elements in a chemical composition?

Question

Hi I am trying to get the percentage of each element from a chemical composition. The following code works well for normal chemical compositions.

comp = "Ag20Al25La55"

re.findall('([A-Z][a-z]?)([0-9]*[.]?[0-9]*)', comp)

output is

[('Ag', '20'), ('Al', '25'), ('La', '55')]

Bur how can I get something similar with the parentheses?

comp = "(Cu60Zr40)98Y2"

The above code would give

[('Cu', '60'), ('Zr', '40'), ('Y', '2')]

But the correct output should be

[('Cu', '58.8'), ('Zr', '39.2'), ('Y', '2')]

Because we have to multiply 98 by 60% to get the percentage for Cu and multiply 98 by 40% to get the percentage for Zr.

Answer 1

You could try:

def compute(x):
  y = float(x.group(2))
  return ''.join([i+str(float(j)*y/100) for i,j in re.findall('([A-z]+)(\\d+[.]?\\d*)', x.group(1))])
  
def final(x): 
    cmp = re.sub('(\\(.*\\))(\\d+)', compute, x)
    return re.findall('([A-Z][a-z]?)([0-9]*[.]?[0-9]*)', cmp)

final(comp)
[('Cu', '58.8'), ('Zr', '39.2'), ('Y', '2')]

Disclaimer: Not the best way to do this