I am trying to substitute values in a column of a data frame that meet a specific condition (in this example behavior == "X") for the previous value in the same column which is not X.
My data looks like the column behavior (see below) and I want to create a new column which need to be like the column behavior2 in which I have substituted the value X with previous known value of behavior which is not X.
What would be the R code to create such a new column in the data frame
Thanks for the help
> dat
time behavior behavior2
1 0 A A
2 50 B B
3 100 B B
4 150 C C
5 200 B B
6 250 A A
7 300 X A
8 350 A A
9 400 A A
10 450 A A
11 500 B B
12 550 X B
13 600 X B
14 650 A A
15 700 C C
16 750 A A
17 800 B B
18 850 X B
19 900 B B
20 950 A A
21 1000 A A
