Question

I have a time series object in R with multiple vectors. I would like to calculate the period-over-period percentage change at each point in time (save t = 1, which would obviously be NA) for each vector.

> data <- ts(data.frame(x1=c(1:10), x2=c(11:20), x3=c(21:30)), start = c(2010,3), frequency = 4)
> data
        x1 x2 x3
2010 Q3  1 11 21
2010 Q4  2 12 22
2011 Q1  3 13 23
2011 Q2  4 14 24
2011 Q3  5 15 25
2011 Q4  6 16 26
2012 Q1  7 17 27
2012 Q2  8 18 28
2012 Q3  9 19 29
2012 Q4 10 20 30

Answer 1

Try this:

R> data/stats::lag(data,-1) - 1
         data.x1   data.x2   data.x3
2010 Q4 1.000000 0.0909091 0.0476190
2011 Q1 0.500000 0.0833333 0.0454545
2011 Q2 0.333333 0.0769231 0.0434783
2011 Q3 0.250000 0.0714286 0.0416667
2011 Q4 0.200000 0.0666667 0.0400000
2012 Q1 0.166667 0.0625000 0.0384615
2012 Q2 0.142857 0.0588235 0.0370370
2012 Q3 0.125000 0.0555556 0.0357143
2012 Q4 0.111111 0.0526316 0.0344828
R>