使用python根据化学式计算分子量

Question

I am using python 2.7.

For example my formula is C6H12O6 . I used this code below

formula='C6H12O6'

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

and got this result:

s= [('C', '6'), ('H', '12'), ('O', '6')]

From here, I'm trying to figure out how to do this:

( C x 6 )+( H x 12 )+( O x 6 )

Can somebody help please, I've been stuck here for almost a day. I also appreciate any other ideas.

Answer 1

You can create a dictionary of weights that map the character of the element to their respective atomic weights, and use the sum() function to do a summation of the list values you have.

weights = {'C': 12, 'H': 1, 'O': 16}
s = [('C', '6'), ('H', '12'), ('O', '6')]

total = sum((weights[e] * int(i)) for e, i in s) # 180

Answer 2

This should work, just get a more complete dictionary (the periodic table) for the entire elem_weight

import re

formula='CH12O6' #example molecule with singular element 

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

elem_weight = {'C': 12, 'H': 1, 'O': 16}

total_weight = 0
for elem, count in s:

    #For singular elements
    if count=='':
        count = 1

    total_weight += int(count)*elem_weight[elem]

print total_weight