Dear all Thanks in advance for replies I am trying to make a barplot out of this data which I read from a file tb <- read.table("tmp.dat" , na.string=c("-")) tmp.dat: ############ (the file is much longer and includes NAs as "-") # A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 2 P 12 2 P 11 2 F 1 2 P 7 2 S 6 2 S 6 2 P 11 2 x 6 2 x 34 2 x 21 2 S 2 3 I 7 3 I 25 3 I 21 2 T 1 3 S 2 3 N 2 3 S 1 2 x 15 3 x 4 3 x 25 3 x 16 3 I 15 4 S 8 4 C 1 4 S 26 3 x 15 4 Y 1 4 S 32 4 x 12 4 S 15 4 x 4 4 x 19 5 P 26 4 x 15 5 P 8 5 L 1 5 R 2 5 P 15 5 S 1 5 P 31 5 x 10 5 x 15 5 x 4 5 R 1 6 I 27 6 I 13 6 I 9 5 x 19 6 N 1 6 M 1 6 x 4 6 I 32 6 x 10 6 N 1 7 E 9 6 N 1 7 E 29 6 x 15 7 x 4 6 x 19 7 x 9 7 D 1 8 T 9 7 D 1 8 R 1 7 E 14 8 x 4 7 E 32 8 T 29 7 x 15 9 V 10 7 x 19 8 x 8 8 T 15 9 x 3 8 T 34 9 V 30 8 x 15 10 P 11 8 x 18 9 x 8 9 V 17 10 x 2 9 I 1 10 H 1 9 x 13 11 V 11 9 V 35 10 P 29 10 A 2 11 x 2 9 x 16 10 x 8 10 P 15 12 K 13 10 P 36 11 V 30 10 S 1 13 L 13 10 x 16 11 x 8 10 x 12 14 K 13 11 V 36 12 K 30 11 V 20 15 P 12 11 x 16 12 R 1 11 x 10 15 [PA] 1 12 K 41 12 x 7 12 K 23 16 G 13 12 x 11 13 L 33 12 R 1 17 M 13 13 I 2 13 x 5 12 x 6 18 D 13 13 L 42 14 K 32 13 L 27 19 G 13 13 x 8 14 N 1 13 x 3 20 P 13 14 K 46 14 x 5 14 K 27 21 K 12 ######### end Data Data explanation : "position" : A1, B1, C1, D1 for different samples [these are amino-acids positions in biological sequences] "value found" : A2, B2, ... "number of occurences" : C1, C2 .... the barplot type I would like to obtain : | | y|| || | || | |||| ... ie : number of occurences (A3, B3, ...) |_______________________________________ PSx PSx FPSTx Px | INx ISx Ix ISx ... ie : values in A2, B2 ....(not always the same "length") 2 | 3 ... ie : position in A1, B1, ... I have tried to read as matrix, simple vectors, but I cannot manage to reach this type of barplot. Any hint towards this goal would be much appreciated All the best Noel