I have a data frame with a variety of stock returns over a period of time. The returns are in percent gain or loss (.02 for 2% return or 102% of the previous periods value).
I am looking for either a function or method to cumulatively show the returns for each period (in percentages). For example, this would show the cumulative/compounding gains for stock1 to be .02, .0404, .09242 for the first 3 periods.... (1.02*1.02*1.05).
mydf = data.frame(period = c('a','b','c','d','e','f'), stock1=c(.02, .02, .05,-.05,-.05,0), stock2=c(0, .01,0,.03,.05,.01))
mydf
#help mydf$stk1_percentgain =
This will give you the cumulative return by period:
sapply(mydf[,-1], function(x) cumprod(1 + x) - 1)
stock1 stock2
[1,] 0.02000000 0.0000000
[2,] 0.04040000 0.0100000
[3,] 0.09242000 0.0100000
[4,] 0.03779900 0.0403000
[5,] -0.01409095 0.0923150
[6,] -0.01409095 0.1032382
Or if you want something that's more human-readable:
sapply(mydf[,-1], function(x) paste0(sprintf("%0.2f", (cumprod(1 + x) - 1)*100, 2),"%"))
stock1 stock2
[1,] "2.00%" "0.00%"
[2,] "4.04%" "1.00%"
[3,] "9.24%" "1.00%"
[4,] "3.78%" "4.03%"
[5,] "-1.41%" "9.23%"
[6,] "-1.41%" "10.32%"