CODEWITHSUNDEEP
rdataframe
lasagna
lasagna

Reputation: 174

How to create a function that includes lagged data, applied to a dataframe?

I want to create the following equation:

enter image description here

So far, I have added a data frame:

df=data.frame(x0=c(0.5, rep(NA, 100)), rep(NA,100)), n=0:100)

But I don't know how to apply a function in the followings x0s that take the lagged value of the column. The idea of N is the times that I want to predict.

enter image description here

Upvotes: 1

Views: 45

Answers (1)

Stefano Barbi
Stefano Barbi

Reputation: 3184

Since it is a recursive function you can use purrr::accumulate

library(purrr)

# Example values
r <- 0.1
k1 <- 0.2
k2 <- 3
q <- 5
Et <- 10

fn <- function(x, n) {
  ## n is discarded
  ((r *x/k1 - 1)*(1- x/k2) -q * Et)  * x
}


accumulate(1:50, fn, .init = 0.5)

#> 
#>  [1]      0.50000    -50.33333   -100.00000   -150.00000   -201.33333
#>  [6]   -255.00000   -312.00000   -373.33333   -440.00000   -513.00000
#> [11]   -593.33333   -682.00000   -780.00000   -888.33333  -1008.00000
#> [16]  -1140.00000  -1285.33333  -1445.00000  -1620.00000  -1811.33333
#> [21]  -2020.00000  -2247.00000  -2493.33333  -2760.00000  -3048.00000
#> [26]  -3358.33333  -3692.00000  -4050.00000  -4433.33333  -4843.00000
#> [31]  -5280.00000  -5745.33333  -6240.00000  -6765.00000  -7321.33333
#> [36]  -7910.00000  -8532.00000  -9188.33333  -9880.00000 -10608.00000
#> [41] -11373.33333 -12177.00000 -13020.00000 -13903.33333 -14828.00000
#> [46] -15795.00000 -16805.33333 -17860.00000 -18960.00000 -20106.33333
#> [51] -21300.00000

Upvotes: 1

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