Group list to make separate lines

[GLORY]

Hello Everyone,

 

I need some help; here is my list in csv

1,21.188,19.762,0.000,L1S
2,31.804,7.629,0.000,L2S
3,44.106,18.077,0.000,L2
4,32.984,30.378,0.000,L1
5,45.117,40.995,0.000,L1
6,56.239,26.671,0.000,L2
7,68.878,36.782,0.000,L2E
8,57.587,50.937,0.000,L1E
9,49.168,65.549,0.000,L1S
10,43.612,72.164,0.000,L1
11,50.491,77.059,0.000,L1
12,55.253,70.179,0.000,L1C
13,41.363,59.993,0.000,L2S
14,34.616,68.460,0.000,L2
15,27.472,64.094,0.000,L2
16,33.954,55.495,0.000,L2C

 

And I want to make that list into something like this,

(setq pt (list (nth 1 ln) (nth 2 ln) (nth 3 ln)))
(setq mylist 
 '(
   (("L1S" (list pt)) ("L1" (list pt))...("L1E" (list pt)))
   (("L2S" (list pt)) ("L2" (list pt))...("L2E" (list pt)))
   (("L1S" (list pt)) ("L1" (list pt))...("L1C" (list pt)))
   (("L2S" (list pt)) ("L2" (list pt))...("L2C" (list pt)))
  )
)

 

In order to plot the lines into groups by creating another set of group of points if the description has "S" or start at the end, say L1S for Line 1 Start.

Thank you in advance.Line1 and 2 Group List.csv