In R, how to sum certain rows of a data frame with certain logic?

Question

Hi experienced R users,

It\'s kind of a simple thing. I want to sum x by Group.1 depending on one controllable variable.

I\'d like

Answer 1

If you want to sum only a subset of your data:

my_data <- data.frame(c("TRUE","FALSE","FALSE","FALSE","TRUE"), c(1,2,3,4,5))
names(my_data)[1] <- "DESCRIPTION" #Change Column Name
names(my_data)[2] <- "NUMBER"      #Change Column Name

sum(subset(my_data, my_data$DESCRIPTION=="TRUE")$NUMBER)

You should get 6.