similar to: Number of NA's in every second column

Hi R-users, I have a simple question for R heavy users. If I have a data frame like this dfr <- data.frame(id=1:16, categ=rep(LETTERS[1:4], 4), var3=c(8,7,6,6,5,4,5,4,3,4,3,2,3,2,1,1)) dfr <- dfr[order(dfr$categ),] and I want to score values or points in variable named "var3" following this kind of logic: 1. the highest value of var3 within category (variable named

Hi R-users, Following this post http://tolstoy.newcastle.edu.au/R/help/06/06/28965.html , how do I get last two rows (or six or ten) by id group out of the data frame? Here the example gives just the last row. Sincere thanks, Lauri [[alternative HTML version deleted]]

Dear useRs, Given this code I end up with a list of class "by": a <- sample(1:5,200,replace=TRUE) b <- sample(c("v1","v2","v3"),200,replace=TRUE) c <- sample(c(11,22,33),200,replace=TRUE) data <- runif(200) grouped <- by(data,list(a,b,c),function(x) {c(min=min(x),max=max(x), median=round(median(x),digits=2),mean=round(mean(x),digits=2))})

Dear R-help community, If I have a data.frame df as follows: > df x1 x2 x3 x4 x5 x6 1 5 5 1 1 2 1 2 5 5 5 5 1 5 3 1 5 5 5 5 5 4 5 5 1 4 5 5 5 5 1 5 2 4 1 6 5 1 5 4 5 1 7 5 1 5 4 4 5 8 5 1 1 1 1 5 9 1 5 1 1 2 5 10 5 1 5 4 5 5 11 1 5 5 2 1 1 12 5 5 5 4 4 1 13 1 5 1 4 4 1 14 1 1 5 4 5 5 15 1 5 5 4

Hi R-users, I have a list a <- list(one=matrix(rnorm(20), 5, 4), two=matrix(rnorm(20, 3, 0.5),5,4)) How to add rowSums (calculated using lapply) to corresponding matrix in this list lapply(a, function(x) rowSums(x)) ?? -Lauri

Is there a R function for sort a data frame by a variable ? I know sort a vector, but I don't know sort a data frame by a column. Can you help me ? the sort() function don't work with data frame.

Dear all, I'm working on a data.frame named en.data, which has n cases and m columns. I generate the correlation matrix of en.data by > cor(en.data) I find that there is no p-value on each correlation in the correlation matrix. I searched in the R-help mail list and found some related posts, but I didn't find direct way to solve the problem. Someone said to use cor.test() or

Dear friends, I'm doing a simulation on logistic regression model, but the programs can't work well,please help me to correct it and give some suggestions. My programs: data<-matrix(rnorm(400),ncol=8) #sample size is 50 data<-data.frame(data) names(data)<-c(paste("x",1:8,sep="")) #8 independent variables,x1-x8; #logistic regression model is

>cbn<-as.matrix(expand.grid( rep( list(0:1), 50))) Error in rep.int(rep.int(seq_len(nx), rep.int(rep.fac, nx)), orep) : invalid 'times' value In addition: Warning message: In rep.int(rep.int(seq_len(nx), rep.int(rep.fac, nx)), orep) : NAs introduced by coercion But I'm only interested in cbn matrix rows where: cbn<- cbn[rowSums(cbn)==5,] Is there a way to evaluate it

Dear all, I think that my question is very simple but I failed to solve it. I have a list which elements are matrices like this: >mylist [[1]] [,1] [,2] [,3] [1,] 1 3 5 [2,] 2 4 6 [[2]] [,1] [,2] [,3] [1,] 7 9 11 [2,] 8 10 12 I'd like to create a matrix M<-mylist[[1]]+mylist[[2]] [,1] [,2] [,3] [1,] 8 12 16 [2,] 10 14 18

I am struggling with R code optimization, a recurrent topic on this list. I have three arrays, say A, B and C, all having the same number of columns. I need to compute an array D whose generic element is D[i, j, k] <- sum_n A[i, n]*B[j, n]*C[k, n] Cycling over the three indices and subsetting the columns won't do. Is there any way to implement this efficiently in R or should I resign to

Dear all, I am trying to extract rows from a data.frame based on the rowSums != 0. I want to preserve rownames in the first column in the subset. Does anyone know how to extract all species that don't have rowSums equal to zero? Here it is: # dataset x <- data.frame( species=c("sp.1","sp.2","sp.3","sp.4"), site1=c(2,3,0,0), site2=c(0,0,0,0),

Dear R-helpers, I need to compute probabilties of multinomial observations, eg by doing the following: y=sample(1:3,15,1) prob=matrix(runif(45),15) prob=prob/rowSums(prob) diag(prob[,y]) However, my question is whether this is the most efficient way to do this. In the call prob[,y] a whole matrix is computed which seems a bit of a waste. Is there maybe a vectorized version of dmultinom which

I have a text file similar to this (separated by spaces): x <- "DF12 This is an example 1 This DF12 This is an 1232 This is DF14 This is 12334 This is an DF15 This 23 This is an example " and I know the field lengths of each variable (there is 5 variables in this data set), which are: varlength <- c(2, 2, 18, 5, 18) How can I import this kind of data into R, using the varlength

Please, I would like to generate a random bistochastic matrix, that is a squared matrix of non-negative numbers with each row and each column sum to 1, for example : .2 .3 .5 .6 .3 .1 .2 .4 .4 I don't know of to code this. Do you have any idea ? Thanks Florent Bresson ___________________________________________________________________________ Demandez ?

Hi, I am trying to do the following computation: p <- rep(0, n) coef <- runif(K+1) U <- matrix(runif(n*(2*K+1)), n, 2*K+1) for (i in 0:K){ for (j in 0:K){ p <- p + coef[i+1]* coef[j+1] * U[,i+j+1] } } I would appreciate any suggestions on how to perform this computation efficiently without the "for" loops? Thank

Hi everybody, Maybe this question is quite simple but i just don't know how to make it. I have a matrix a somewhat like this one but bigger: > a f g h i j k a NA NA 11 16 21 26 b NA NA 12 17 22 27 c NA 8 13 18 23 28 d NA 9 14 19 24 29 e NA 10 15 20 25 30 And i want to get the rows which at most have 2 Na. Thanks in advance. Shi Jiantao [[alternative HTML version deleted]]

R users, I have a simple lapply question. g <- list(a=1:3, b=4:6, c=7:9) g <- lapply(g, function(x) as.data.frame(x)) lapply(g, function(x) cbind(x, var1 = rep(names(g), each=nrow(x))[1:nrow(x)])) I get $a x var1 1 1 a 2 2 a 3 3 a $b x var1 1 4 a 2 5 a 3 6 a $c x var1 1 7 a 2 8 a 3 9 a And I would like to have $a x var1 1 1 a 2 2 a 3 3 a

Dear list, I tried to find a solution for this problem from the archives but couldn't find any. I would like sample sequence of ten days from vector d d <- seq(as.Date("2007-02-12"), as.Date("2008-08-18"), by="days") so that the days follow each other (sample(d, 10) is not the appropriate solution). Any ideas? Best regards, Lauri

Hello, I have some Inf values in a matrix, but I don't want to replace them with some value but rather remove the rows that contain the Inf values. Also I would like to record the rows which were removed. Is there an easy way to do this instead of writing loops over the matrix? Thanks. Ita Cirovic Donev