Question

Assume I have a dataframe df with one column namely time. Now, I’d like to add a new column to the dataframe accumulated as seen below, that sums up the values from df.time for each row.

    time     accumulated
1   10       10
2   12       22
3   14       36
4   6        42  

A quick hint would be really nice!

Answer 1

For these simple tasks there is usually a build-in function. Of course, knowing what the mathematical operation is called helps finding these functions. You want the cumulative sum.

df <- data.frame(time=c(10,12,14,6))

df$accumulated <- cumsum(df$time)

#  time accumulated
#1   10          10
#2   12          22
#3   14          36
#4    6          42