Modify Strings in cell array according to pattern

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I have to cell arrays A & B
A = ['C1 H2 O1 N1 S1';
'C5 H2 O0 N1 S0';
'C2 H6 O0 N1 S1';
'C2 H6 O2 N1 S0';
'C3 H10 O1 N1 S0';
'C6 H5 O2 N2 S1';
'C8 H9 O4 N0 S0';
'C9 H13 O3 N0 S0';
'C10 H17 O2 N0 S0';
'C11 H21 O1 N0 S0';
'C12 H25 O0 N0 S0'];
B = ['C5H9O2+'
and I would like to have B in the same pattern as A so that (C* H* O* N* S*)
and deleting the +
B[1] = 'C5 H9 O2 NO S0'
kinda tried with regexprep() but didn't get anything by now.....

Accepted Answer

Allen on 20 Jan 2020
Let me know how this works for you.
B = {'C3H7O';'C2H7O2';'C2H7O2+';'C4H5O';'C4H5O';'C3H3O2';'';'C4H7O';'C3H5O2';'C3H7O2';'C2H5O3';...
I = {'C0','H0','O0','N0','S0'};
B = regexprep(B,{'\W','(?![CHONS]\d+)[CHONS]'},''); % Removes all but letter/number pairs
B(cellfun(@isempty,B)) = join(I,''); % Replaces empty cells with I
% Adds missing letter/number pairs to each cell of B and joins with no spacing
expr = {'(C\d+)','(H\d+)','(O\d+)','(N\d+)','(S\d+)'};
for i=1:size(B,1)
B(i) = join([B{i},I(cellfun(@isempty,regexp(B{i},expr)))],'');
% Adds a single space between letter/number pairs
B = regexprep(B,'(C\d+)(H\d+)(O\d+)(N\d+)(S\d+)','$1 $2 $3 $4 $5');
Martin Muehlegger
Martin Muehlegger on 14 Feb 2020
And here we are,.... I have to tweak the code,
My new B is
B = ['C9H19NO2', 'C9H20O3', 'C6H12O6', 'C11H20O2', 'C10H19NO2', 'C10H21NO2', ...
'C10H20O3', 'C11H19NO2', 'C11H18O3', 'C12H22O2', 'C11H21NO2', 'C11H20O3']
So the order has changed to CHNOS and i would like to have it in the order as before CHONS and filled up with letter/number pair to each cell of B
PS: found a problem in the first code, when in B some letter without a number was found it shouldn't be zero e.g.
'C3H7O' = C3 H7 O0 N0 S0
but instead it should be
'C3H7O' = C3 H7 O1 N0 S0
because there is one 'O'

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More Answers (1)

Allen on 16 Jan 2020
I am sure that there is a much more elegant method using just regular expressions, but the following should give you what you are looking for if your input cell-array is similar to the example provided.
B = {'C5H9O2+'
I = {'C','H','O','N','S'};
% Looks for 'C', 'H', 'O', 'N',and 'S' and when not present in a cell-array element, append the
% missing charater followed by a '0' to the cell-array element.
for i=1:length(I)
idx = ~contains(B,I{i});
B(idx) = append(B(idx),I{i},'0');
% Use regular expression to replace all non-alphanumeric or underscore characters, then find
% matching tokens consisting of 'C', 'H', 'O', 'N', and 'S' each followed by any number of digits
% and recombine them as a single space-delimited string.
regexprep(B,{'\W','(C\d*)(H\d*)(O\d*)(N\d*)(S\d*)'},{'','$1 $2 $3 $4 $5'})
Martin Muehlegger
Martin Muehlegger on 17 Jan 2020
Matlab 2017b
whos B
Name Size Bytes Class Attributes
B 177x1 21946 cell

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