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			| Re: Row Wise Sum [message #1927 is a reply to message #1926] | Tue, 13 June 2023 20:49   |  
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					|  nbehrnd Messages: 234
 Registered: June 2019
 | Senior Member |  |  |  
	| Dear Angus, 
 to answer the first question, you need a placeholder which either returns `0` (if there is nothing in the cell), or the value of the cell (if the cell contains an entry acceptable for an addition); `replaceempty` is suitable here.  For the second question, you already tap against a good door; you now need to know how to negate a Boolean in DataWarrior's syntax.
 
 For the purpose of illustration, I attach a minimal working example below.  Departing from a small library of random molecules, DataWarrior computes the number of H-Donors and H-Acceptors.  Manually added -- leaving some gaps is intentional -- two additional columns with manual entries, `counter_a` and `counter_b`.  The `special_sum` then
 
 
 either adds either the results of DataWarrior's intrinsic functions plus the zeroes, or the values of the additional columns.  To count the the non-empty columns `!` offers to define
HAcceptors + HDonors + replaceempty(counter_a, 0) + replaceempty(counter_b, 0)
 
 You can access, adjust and update the equations in question in the header cell of the corresponding column 7 and 8 (clique with the right mouse button).
!isempty(HAcceptors) + !isempty(HDonors) + !isempty(counter_a) + !isempty(counter_b)
 With regards,
 
 Norwid
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