Summary count by multiple groups with condition in dplyr

Question

I have a dataframe that looks like this:

data <- data.frame(a=c(1,1,0,0,0,0,1,1,1, 0), 
               b=c(\"x\",\"x\",\"x\",\"x\",\"x\",\"y\",\"y\",\"y\",\"z         


        

Answer 1

We can use

library(dplyr) 
data %>%
     group_by(d, b) %>% 
     summarise(e = sum(c[a==1], na.rm = TRUE))

---

Or

data %>%
      group_by(d, b) %>% 
      summarise(e = sum((a==1)*c, na.rm = TRUE))