How to extract info from a chemical formula
조회 수: 17 (최근 30일)
이전 댓글 표시
Hi All, I want to break down a chemical formula into its constituents. For example: Silicon Dioxide = SiO2 I want to take the string 'SiO2' and parse it so that I know I have 1 silicon and 2 oxygens. I want to do this for more complex compounds as well, say Polyimide which is 'C22H10N2O5'. So I need to handle upper case and lower case letters, and 1 or 2 digit numbers. Any help would be much appreciated.
Pat
댓글 수: 0
답변 (4개)
Fangjun Jiang
2011년 8월 12일
Use the combination of isstrprop() and regexp() might help. You need to provide more examples and explain what you want.
str='C22H10N2O5'
num=regexp(str,'\d+','match')
isstrprop(str,'alpha')
isstrprop(str,'digit')
isstrprop(str,'upper')
One solution:
str='C22H10PuCrN2O5';
[EleList,Trash,EleEnd]=regexp(str,['[','A':'Z','][','a':'z',']?'],'match');
[Num,NumStart]=regexp(str,'\d+','match');
NumList=ones(size(EleList));
Index=ismember(EleEnd+1,NumStart);
NumList(Index)=cellfun(@str2num,Num);
댓글 수: 3
Fangjun Jiang
2011년 8월 12일
Please refresh my memory. Is it true that the element can only have two or one letter? If it is two-letter, is it true that the first letter is always uppercase and the second letter is lowcase?
Paulo Silva
2011년 8월 12일
look at any periodic table that you might find online, all symbols should be there
Paulo Silva
2011년 8월 12일
That's not easy to do, for example not all formulas have the constituents separated by a number, you also need to have all possible constituents in a list so you can identify them in any formula and after it check if there's a number after each constituents.
댓글 수: 1
Kelly Kearney
2011년 8월 12일
Well, assuming he's not dealing with any of those U** elements at the upper end of the periodic table, then all elements consist of either one capital letter or a capital and lowercase letter. So it should be pretty easy to pick those out. Will you always have the base formula, or will it be arranged structurally (i.e. Si(OH)4, or SiO4H4?)
Patrick Knapp
2011년 8월 12일
댓글 수: 1
Fangjun Jiang
2011년 8월 12일
Nice! I couldn't resist coming up with a no-loop solution. See my updated answer.
phenan08
2023년 1월 26일
If it can help, I wrote a formula string parser to determine the composition of a molecule, element by element.
It is possible to use semi-developped formulas, and the script returns 4 outputs: the raw molecular formula, the composition table (the different elements with their counts), the average MW and the monoisotopic mass.
댓글 수: 0
참고 항목
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!