I am very new to R.

I have a large data frame and I need to sum the row values in a particular fashion and create a new data frame with the results. For example, my input data frame is something like:

I need to create a new data frame with each row adding the 'avg' value from the following row. To make it more clear: My output would look something like:

Where r1_2 is the sum 'avg' in rows 1 and 2; r1_2_3 is the sum of 'avg' in rows1, 2 and 3; r1_2_3_4 is the sum of 'avg' for in rows 1, 2, 3 and 4... and so on... I have several rows (40). I would like a row name that represents the value (like r1_2, r1_2_3, r1_2_3_4 or similar.

I tried to do it manually but it is very error prone and takes forever to write. Can someone please suggest a cleaner way to do it?

CodePudding user response：

INPUT is your input table. I added columns with the wanted results.

Create the row names for the output by using the paste function

INPUT$file <- paste0("r",sapply(1:nrow(INPUT),function(X) paste0(1:X,collapse = "_")))

use built in function

INPUT$sum_avg <- cumsum(INPUT$avg)

result

INPUT
   f avg set other     file sum_avg
1 r1   2   6     1       r1       2
2 r2   4  12     2     r1_2       6
3 r3   3  27     3   r1_2_3       9
4 r4   1   3     2 r1_2_3_4      10