Dear list,
Im trying to do the following operation but im not able to do it
This is my table:
1 2 3
1 0 7 4
2 0 2 0
3 0 1 3
4 0 3 4
what i would like to do is
divide each row values with the corresponding column' sum,namely:
1 2 3
1 0 0.54 0.36
2 0 0.15 0
3 0 0.08 0.27
4 0 0.23 0.36
thanks for your attention
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On 06-May-10 17:06:26, n.vialma at libero.it wrote:> > Dear list, > Im trying to do the following operation but im not able to do it > This is my table: > 1 2 3 > 1 0 7 4 > 2 0 2 0 > 3 0 1 3 > 4 0 3 4 > > what i would like to do is > > divide each row values with the corresponding column' sum,namely: > > 1 2 3 > 1 0 0.54 0.36 > 2 0 0.15 0 > 3 0 0.08 0.27 > 4 0 0.23 0.36 > > thanks for your attentionThere is a problem with the first columns, because it's sum is 0, so you would be doing "0/0", with result "NaN". So, for illustration (and to allow easy verification) I've replaced your first column with 1,2,3,4. Suppose your table is a matrix: M <- matrix(c(1,2,3,4,7,2,1,3,4,0,3,4),ncol=3) M # [,1] [,2] [,3] # [1,] 1 7 4 # [2,] 2 2 0 # [3,] 3 1 3 # [4,] 4 3 4 Note that the entries are given in the order of moving down successive columns. That is what a mtrix is: a vector of numbers, in that order, with in addition a "dim" attribute: dim(M) # [1] 4 3 Now you can do the clever bit. Transpose the matrix M: tM <- t(M) tM # [,1] [,2] [,3] [,4] # [1,] 1 2 3 4 # [2,] 7 2 1 3 # [3,] 4 0 3 4 This is a new matrix whose elements will again be read in the order of going down succesive columns, i.e. as c(1,7,4,2,2,0,3,1,3,4,3,3) Now compute the column sums of tM: Csums <- colSums(tM) Csums # [1] 10 13 11 Now, in the expression "tM/Csums", the successive elements of tM, in the above order, will be divided by the successive elements of Csums, with Csums being recycled until it is finished: tM/Csums # [,1] [,2] [,3] [,4] # [1,] 0.1000000 0.2000000 0.30000000 0.4000000 # [2,] 0.5384615 0.1538462 0.07692308 0.2307692 # [3,] 0.3636364 0.0000000 0.27272727 0.3636364 But this is the transpose of what you want, so transpose it back to t(tM/Rsums). So, just as a full check: M # [,1] [,2] [,3] # [1,] 1 7 4 # [2,] 2 2 0 # [3,] 3 1 3 # [4,] 4 3 4 Csums <- colSums(M) Csums # [1] 10 13 11 t(tM/Csums) # [,1] [,2] [,3] # [1,] 0.1 0.53846154 0.3636364 # [2,] 0.2 0.15384615 0.0000000 # [3,] 0.3 0.07692308 0.2727273 # [4,] 0.4 0.23076923 0.3636364 Explicitly: the division of t(M) = # [,1] [,2] [,3] [,4] # [1,] 1 2 3 4 # [2,] 7 2 1 3 # [3,] 4 0 3 4 by Csums=c(10,13,11) has been done as 1/10,7/13,4/11, 2/10,2/13,0/11, 3/10,1/13,3/13, 4/10,3/13,4/11 Hoping this helps, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 06-May-10 Time: 19:08:51 ------------------------------ XFMail ------------------------------
For completeness. On Thu, May 6, 2010 at 8:03 PM, Joris Meys <jorismeys@gmail.com> wrote:> Table <- matrix(ncol=3,nrow=4,c(0,0,0,0,7,2,1,3,4,0,3,4)) > > # one way > t(t(Table)/colSums(Table)) > > # another way > apply(Table,2,function(x){x/sum(x)}) > > Take in mind that your solution is wrong. If you divide 0 by 0, you get > NaN. If you want this not to happen, you'll have to add an extra control. >> On Thu, May 6, 2010 at 7:06 PM, n.vialma@libero.it <n.vialma@libero.it>wrote: > >> >> Dear list, >> Im trying to do the following operation but im not able to do it >> This is my table: >> 1 2 3 >> 1 0 7 4 >> 2 0 2 0 >> 3 0 1 3 >> 4 0 3 4 >> >> what i would like to do is >> >> divide each row values with the corresponding column' sum,namely: >> >> 1 2 3 >> 1 0 0.54 0.36 >> 2 0 0.15 0 >> 3 0 0.08 0.27 >> 4 0 0.23 0.36 >> >> >> thanks for your attention >> >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. >> > > > > -- > Joris Meys > Statistical Consultant > > Ghent University > Faculty of Bioscience Engineering > Department of Applied mathematics, biometrics and process control > > Coupure Links 653 > B-9000 Gent > > tel : +32 9 264 59 87 > Joris.Meys@Ugent.be > ------------------------------- > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php >-- Joris Meys Statistical Consultant Ghent University Faculty of Bioscience Engineering Department of Applied mathematics, biometrics and process control Coupure Links 653 B-9000 Gent tel : +32 9 264 59 87 Joris.Meys@Ugent.be ------------------------------- Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php [[alternative HTML version deleted]]
Hello, I just got JGR, and it seems greet. One issue is the default font of the editor is terrible... Anybody have a good one ? Thanks
Hello, I just got JGR ( running on Windows 7 ), and it seems greet. One issue is the default font of the editor is terrible... Anybody have a good one ? Thanks
Hi: There's always prop.table: I read in your data as a data frame d. Since prop.table() expects a matrix/array as input,> prop.table(as.matrix(d), 2)V2 V3 V4 [1,] NaN 0.53846154 0.3636364 [2,] NaN 0.15384615 0.0000000 [3,] NaN 0.07692308 0.2727273 [4,] NaN 0.23076923 0.3636364 where the second argument indicates that you want column proportions. You can always use round(prop.table(as.matrix(d), 2), 2) to simplify the output to two decimal places. (As you can see, Dr. Harding's comment about zero columns is well placed...) HTH, Dennis On Thu, May 6, 2010 at 10:06 AM, n.vialma@libero.it <n.vialma@libero.it>wrote:> > Dear list, > Im trying to do the following operation but im not able to do it > This is my table: > 1 2 3 > 1 0 7 4 > 2 0 2 0 > 3 0 1 3 > 4 0 3 4 > > what i would like to do is > > divide each row values with the corresponding column' sum,namely: > > 1 2 3 > 1 0 0.54 0.36 > 2 0 0.15 0 > 3 0 0.08 0.27 > 4 0 0.23 0.36 > > > thanks for your attention > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. >[[alternative HTML version deleted]]