Calculating column differences
Dear Jeff, Rather than diff-ing a linear vector you're trying to diff values from two different rows. Also you indicate that you want to place the diff-ed value in the 'lower' row of a new column. Try this (note insertion of an initial "zero" row):
df <- data.frame(ID=1:5,Score=4*2:6) df1 <- rbind(c(0,0), df) cbind(df1, "diff"=c(0, diff(df1$Score)) )
ID Score diff 1 0 0 0 2 1 8 8 3 2 12 4 4 3 16 4 5 4 20 4 6 5 24 4
HTH, Bill. W. Michels, Ph.D.
On Wed, Mar 24, 2021 at 9:49 AM Jeff Reichman <reichmanj at sbcglobal.net> wrote:
r-help forum
I'm trying to calculate the diff between two rows and them mutate the
difference into a new column. I'm using the diff function but not giving me
what I want.
df <- data.frame(ID=1:5,Score=4*2:6)
What a want where
ID Score diff
1 1 8 8
2 2 12 4
3 3 16 4
4 4 20 4
5 5 24 4
What I am getting
ID Score diff
1 1 8 NA
2 2 12 4
3 3 16 4
4 4 20 4
5 5 24 4
Jeff
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