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rdataframesubtraction

Subtract next value from present R

What I want to do in my dataframe is create a new column with the value from the subtraction of the present value (n), subtracted to the next value (n + 1), so it is: (n + 1) - (n).

The diff() command does the (n) - (n - 1).

For example:

Id  Value   Diff    Diff_Wanted
1   120     NA      2
2   122     2       3
3   125     3       3
4   128     3       6
5   134     6       6
6   140     6       12
7   152     12      8
8   160     8       NA

Diff_Wanted is the desired column to be added in the data frame.

Solution 
  • library(dplyr)
df %>% mutate(Diff_Wanted = lead(Value - lag(Value)))
# A tibble: 8 x 4
     Id Value  Diff Diff_Wanted
  <dbl> <dbl> <dbl>       <dbl>
1     1   120    NA           2
2     2   122     2           3
3     3   125     3           3
4     4   128     3           6
5     5   134     6           6
6     6   140     6          12
7     7   152    12           8
8     8   160     8          NA