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I work as a boat designer and often require calculating total length of polyline & centre of gravity (both open & closed polylines). I have a snippet below to show the sample code I am currently using - this only works with a group of lines - it doesnt work with polylines. Currently everytime I have to calculate the CG, I have to copy the polyline over, explode it & select the lines to calculate the CG. The logic is as follows - assuming we have 3 segments on the polyline(A,B,C) : Centre of Gravity of Polyline = (Len of A multiplied by Centroid of A + Len of b multiplied by Centroid of B + Len of C multiplied by Centroid of C) divided by Total Length of polyline I am new to LISP & although have some background in other programming languages, find it is relatively difficult to write the code, the syntax being very different. I found a similar code ( TotalADD Total Addition by Andrea Andreetti & modified to come to the below code). It would be ideal if I can select a group of polylines (using select similar) and run the command to get a text table in autocad with CG & total length calculated for set of polylines on different layers. But I am not sure how this can be achieved. Would you be able to help or am I asking for too much ? any guidance will be much appreciated. (if (eq (vla-get-objectname n) "AcDbLine") (progn (setq itemlinelength (+ itemlinelength (vla-get-length n))) (setq StartPoint(vlax-safearray->list (vlax-variant-value (vla-get-startpoint n)))) (setq x1 (car Startpoint)) (setq y1 (cadr Startpoint)) (setq EndPoint(vlax-safearray->list (vlax-variant-value (vla-get-endpoint n)))) (setq x2 (car endpoint)) (setq y2 (cadr endpoint)) (setq xmid (* (+ x1 x2) 0.5)) (setq ymid (* (+ y1 y2) 0.5)) (setq xmom (* xmid (vla-get-length n))) (setq ymom (* ymid (vla-get-length n))) (setq itemxmoment (+ itemxmoment xmom)) (setq itemymoment (+ itemymoment ymom)) ) ) (setq totxcg (/ itemxmoment itemlinelength)) (setq totycg (/ itemymoment itemlinelength)) (setq tlength (rtos itemlength 2 ) (setq totxcg (rtos totxcg 2 ) (setq totycg (rtos totycg 2 ) (acet-ui-status (strcat "Length: " tlength "\n" "X CoG Pos: " totxcg "\n" "Y CoG Pos: " totycg "\n" )