Adel, I don't fully understand your question. Please try to explain what you want to do again. In general to change a data frame to a matrix, all one needs to do is use the as.matrix function.
# Create dataframe mydataframe1 <- data.frame(x=1:3, y=10:12) mydataframe1 class(mydataframe1) # Convert to matrix mymatrix1 <- as.matrix(mydataframe1) mymatrix1 class(mymatrix1) You must remember that data frames can contain values expressed as numbers or characters. A matrix on the other hand normally contains only numbers. Thus trying to convert a dataframe, such as yours to a matrix will result in something that you probably don't want. Note the elements in the matrix are all character values, and you probably want numeric values: # Create dataframe mydataframe2 <- data.frame(x=1:3, y=10:12, letters = c("a","b","c")) mydataframe2 class(mydataframe2) # Convert to matrix mymatrix2 <- as.matrix(mydataframe2) mymatrix2 class(mymatrix2) John John David Sorkin M.D., Ph.D. Chief, Biostatistics and Informatics University of Maryland School of Medicine Division of Gerontology Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 (Phone) 410-605-7119 (Fax) 410-605-7913 (Please call phone number above prior to faxing) >>> Adel ESSAFI <adeless...@gmail.com> 2/18/2012 7:57 AM >>> Hello > orderulcount Group.1 Group.2 Group.3 x V5 7 C L 0.0 30 C / L 19 C L 0.2 27 C / L 31 C L 0.4 15 C / L 43 C L 0.6 7 C / L 54 C L 0.8 2 C / L 10 C S 0.0 27 C / S 22 C S 0.2 10 C / S 34 C S 0.4 6 C / S 46 C S 0.6 1 C / S 1 D D 0.0 30 D / D 13 D D 0.2 30 D / D 25 D D 0.4 17 D / D 37 D D 0.6 9 D / D 49 D D 0.8 2 D / D 3 D F 0.0 30 D / F 15 D F 0.2 26 D / F 27 D F 0.4 13 D / F 39 D F 0.6 3 D / F 51 D F 0.8 3 D / F 5 D I 0.0 26 D / I 17 D I 0.2 7 D / I 29 D I 0.4 7 D / I 41 D I 0.6 1 D / I 53 D I 0.8 1 D / I 8 D L 0.0 30 D / L 20 D L 0.2 26 D / L 32 D L 0.4 14 D / L 44 D L 0.6 8 D / L 55 D L 0.8 2 D / L 11 D S 0.0 27 D / S 23 D S 0.2 8 D / S 35 D S 0.4 4 D / S 47 D S 0.6 1 D / S 2 I D 0.0 30 I / D 14 I D 0.2 30 I / D 26 I D 0.4 14 I / D 38 I D 0.6 9 I / D 50 I D 0.8 2 I / D 4 I F 0.0 30 I / F 16 I F 0.2 29 I / F 28 I F 0.4 16 I / F 40 I F 0.6 5 I / F 52 I F 0.8 2 I / F 6 I I 0.0 30 I / I 18 I I 0.2 17 I / I 30 I I 0.4 4 I / I 42 I I 0.6 1 I / I 9 I L 0.0 30 I / L 21 I L 0.2 27 I / L 33 I L 0.4 17 I / L 45 I L 0.6 8 I / L 56 I L 0.8 2 I / L 12 I S 0.0 28 I / S 24 I S 0.2 11 I / S 36 I S 0.4 6 I / S 48 I S 0.6 3 I / S I have a data frame formed by 5 colomns. How to transform this data frame to a matrix formed as follow: 1. the colomn 5 is the comumn (string) 2. the colomn 5 row 3. the data are the colomn x. I aim to draw barplot later using the matrix. Thanks for any help -- PhD candidate in Computer Science Address 3 avenue lamine, cité ezzahra, Sousse 4000 Tunisia tel: +216 97 246 706 (+33640302046 jusqu'au 15/6) fax: +216 71 391 166 [[alternative HTML version deleted]] Confidentiality Statement: This email message, including any attachments, is for th...{{dropped:6}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.