sapply

Probably this would be easy. I have a Matrix: testM <- matrix(1:40, ncol = 4, byrow = FALSE) testM [,1] [,2] [,3] [,4] [1,] 1 11 21 31 [2,] 2 12 22 32 [3,] 3 13 23 33 [4,] 4 14 24 34 [5,] 5 15 25 35 [6,] 6 16 26 36 [7,] 7 17 27 37 [8,] 8 18 28 38 [9,] 9 19 29 39 [10,] 10 20 30 40 and I want to "reduce" the matrix summing column pairs by row. Expected result: [,1] [,2] [1,] 12 52 [2,] 14 54 [3,] 16 56 [4,] 18 58 [5,] 20 60 [6,] 22 62 [7,] 24 64 [8,] 26 66 [9,] 28 68 [10,] 30 70 I tried this but doesn't work X <- apply(1:(ncol(testM)/2), 1, function(x) sum(testM[x], testM[x+1]) ) Error in apply

I'm trying to calculate the mean and standard deviation of several columns (except the first column) in a data.frame with NA values. I've tried colMeans , sapply , etc., to create a loop that runs through the data.frame and then stores means and standard deviations in a separate table but keep getting a "FUN" error. any help would be great. Thanks a sapply(df, function(cl) list(means=mean(cl,na.rm=TRUE), sds=sd(cl,na.rm=TRUE))) col1 col2 col3 col4 col5 means 3 8 12.5 18.25 22.5 sds 1.581139 1.581139 1.290994 1.707825 1.290994 as.data.frame( t(sapply(df, function(cl) list(means=mean(cl,na.rm

I am using the bit64 package in some R code. I have created a vector of 64 bit integers and then tried to use sapply to iterate over these integers in a vector. Here is an example: v = c(as.integer64(1), as.integer64(2), as.integer64(3)) sapply(v, function(x){is.integer64(x)}) sapply(v, function(x){print(x)}) Both the is.integer64(x) and print(x) give the incorrect (or at least) unexpected answers (FALSE and incorrect float values). I can circumvent this by directly indexing the vector c but I have two questions: Why the type conversion? Is their some rule R uses in such a scenario? Any way

I'm sure this is very simple, and I think it's a case of using separate and gather. I have a single field in a dataframe, authorlist,an edited export of a pubmed search. It contains the authors of the publications. It can, obviously, contain either a single author or a collaboration of authors. For example this is just a selection of the options available: Author Drijgers RL, Verhey FR, Leentjens AF, Kahler S, Aalten P. What I'd like to do is create a single list of ALL authors so that I'd have something like Author Drijgers RL Verhey FR Leentjens AF Kahler S Aalten P How do I do that? I

Edited df and dict I have a data frame containing sentences: df <- data_frame(text = c("I love pandas", "I hate monkeys", "pandas pandas pandas", "monkeys monkeys")) And a dictionary containing words and their corresponding scores: dict <- data_frame(word = c("love", "hate", "pandas", "monkeys"), score = c(1,-1,1,-1)) I want to append a column "score" to df that would sum the score for each sentence: Expected results text score 1 I love pandas 2 2 I hate monkeys -2 3 pandas pandas pandas 3 4 monkeys monkeys -2 Update Here are the results so far: Akrun's methods Suggestion 1 df %>% mutate(score