Sum rows in data.frame or matrix

r dataframe matrix rowsum
user483502 picture user483502 · Oct 21, 2010 · Viewed 346.8k times · Source

I have a very large dataframe with rows as observations and columns as genetic markers. I would like to create a new column that contains the sum of a select number of columns for each observation using R.

If I have 200 columns and 100 rows, I would like a to create a new column that has 100 rows with the sum of say columns 43 through 167. The columns have either 1 or 0. With the new column that contains the sum of each row, I will be able to sort the individuals who have the most genetic markers.

I feel it is something close to:

data$new=sum(data$[,43:167])

Answer

Greg picture Greg · Oct 21, 2010

you can use rowSums

rowSums(data) should give you what you want.

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