R how can I calculate difference between rows in a data frame

Question

Here is a simple example of my problem:

> df <- data.frame(ID=1:10,Score=4*10:1)
> df
       ID Score
    1   1    40
    2   2    36
    3   3    3         


        

Answer 1

Perhaps you are looking for something like this:

> tail(df, -1) - head(df, -1)
   ID Score
2   1    -4
3   1    -4
4   1    -4
5   1    -4
6   1    -4
7   1    -4
8   1    -4
9   1    -4
10  1    -4

You can subtract or add two data.frames together if they are the same dimensions. So, what we are doing here is subtracting one data.frame that is missing the first row (tail(df, -1)) and one that is missing the last row (head(df, -1)) and subtracting them.