[datatable-help] Sistematically construction of 2 variables in data table

[Frank S.]

Hi all,  I have been able to solve (I think) the second question: newdt[, init := c( round(difftime(start[1], bday[1])/365.25,1) , 
 round(difftime(dsum[1:(.N-1)],bday[1:(.N-1)])/365.25,1) )][] #  [] is to print the result    		 	   		  
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