How to sum data.frame column values?

Question

I have a data frame with several columns; some numeric and some character. How to compute the sum of a specific column? I’ve googled for this and I see nume

Answer 1

To sum values in data.frame you first need to extract them as a vector.

There are several way to do it:

# $ operatior
x <- people$Weight
x
# [1] 65 70 64

Or using [, ] similar to matrix:

x <- people[, 'Weight']
x
# [1] 65 70 64

Once you have the vector you can use any vector-to-scalar function to aggregate the result:

sum(people[, 'Weight'])
# [1] 199

If you have NA values in your data, you should specify na.rm parameter:

sum(people[, 'Weight'], na.rm = TRUE)