There are other posts about row-wise operators on datatable. They are either too simple or solves a specific scenario My question here is more generic. There is a solution using dplyr. I have play...

I am working in R, and would prefer a dplyr solution if possible. sample data: data.frame( col1 = c("a", "b", "c", "d"), col2 = c("a", "b&qu...

This is somehow related to this question: In principle I try to understand how rowwise operations with mutate across multiple columns applying more then 1 functions like (mean(), sum(), min() etc.....

I have a dataframe that has lots of columns that are something like this: data <- data.frame (a.1 = 1:5, a.2b = 3:7, a.5 = 5:9, bt.16 = 4:8, bt.12342 = 7:11) I'd like a result with columns that...

I have a data table with probabilities for a discrete distribution stored in columns. For example, dt <- data.table(p1 = c(0.5, 0.25, 0.1), p2 = c(0.25, 0.5, 0.1), p3 = c(0.25, 0.25, 0.8)) I'd l...

I'm trying to automatically calculate the mean score per row for multiple groups of columns. E.g. a set of columns could represent items of different scales. The columns are also systematically nam...

ID <- 1:6 math <- c("YES","NO","YES","NO",NA,NA) history <- c(NA,NA,"NO","NO","YES",NA) dt <- data.frame(ID, math,...

I will use the following data set to illustrate my questions: my_df <- data.frame( a = 1:10, b = 10:1 ) colnames(my_df) <- c("a", "b") Part 1 I use the mutate() function to create two n...

If I wanted to sum over some variables in a data-frame using dplyr, I could do: > head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0....

I'm having trouble using rowwise() to count the number of NAs in each row. My minimal example: df <- data.frame(Q1 = c(rep(1, 1), rep(NA, 9)), Q2 = c(rep(2, 2), rep(NA, 8)), Q3 = c(rep(3, 3), ...

I need to find the minimum values of three columns that are bigger than the values in another column. Say these five individuals entered a hospital in different months of the year, and they suffere...

I have a dataframe in R. For each row, I would like to select which column has the highest value, and paste the name of that column. This is simple when there are only two columns to chose from (no...

I have this df: df <- structure(list(a = 1:5, b = 6:10, c = 11:15, d = c("a", "b", "c", "d", "e"), e = 1:5), row.names = c(NA, -5L), class = c(...

Does the following code represent the preferred procedure for traversing the rows of an R data.table and passing the values found at each row to a function? Or is there a more performant way to do ...

I have a data.frame that contains 4 columns (given below). I want to find the index of the minimum column (NOT THE VALUE) for each row. Any idea hiw to achieve that? > d V1 V2 V3 V4 1 0.38811...

I'm trying to return a list using mutate and rowwise but get the error shown in the code. These questions Q1 Q2 helped, but I'd like to keep it simple by iterating over rows using rowwise(), and th...

I need to find the row-wise minimum of many (+60) relatively large data.frame (~ 250,000 x 3) (or I can equivalently work on an xts). set.seed(1000) my.df <- sample(1:5, 250000*3, replace=TRUE)...

As a follow-up to this oldie but goodie: efficient row-wise operations on a data.table I have some data that (unfortunately) look like: library('data.table') set.seed(1234) m <- 5 n <- 7 rb...

Although I've figured this out before, I still find myself searching (and unable to find) this syntax on stackoverflow, so... I want to do row wise operations on a subset of the data.table's colum...

Recently I ran into the data.table package. I'm still not sure how to do row-wise matrix operations. Was it originally intended to handle such operations? For example, what would be data.table equi...