recursion with pmap (enclosed reprex)

[Marcell]

Hi,

I would like to ask that do you know a way to use a loop based recursion with pmap.
(I would like to draw a Solow diagram). Codes enclosed.

library(tidyverse)

K_way <- function(K0 = 100, s, d, A, L, alpha = .3) {
  K <- c(K0)
  for (i in 2:length(s)) { # loop
    Y <- A[i-1]*(K[i-1]^alpha*L[i-1]^(1-alpha))
    K[i] <- K[i-1]*(1-d[i]) + s[i]*Y
  } 
  return(K)
}

df <- tibble(t = 1:100) %>% 
  mutate(
    s = .3, n = .05, d = .1, g = ifelse(t < 30, .03, .01),
  ) %>% 
  mutate(
    A = cumprod(1 + g),
    L = 100*cumprod(1 + n),
  )

K_way(100, df$s, df$d, df$A, df$L, .3) # numric vector w appropriate length
#>   [1]    100.0000    121.9736    145.9455    172.0316    200.3779    231.1589
#>   [7]    264.5774    300.8641    340.2786    383.1105    429.6815    480.3471
#>  [13]    535.4993    595.5695    661.0320    732.4070    810.2657    895.2341
#>  [19]    987.9985   1089.3106   1199.9942   1320.9518   1453.1714   1597.7355
#>  [25]   1755.8296   1928.7519   2117.9241   2324.9033   2551.3946   2799.2654
#>  [31]   3059.8574   3334.0502   3622.7977   3927.1286   4248.1483   4587.0404
#>  [37]   4945.0701   5323.5874   5724.0314   6147.9348   6596.9292   7072.7508
#>  [43]   7577.2466   8112.3815   8680.2450   9283.0600   9923.1903  10603.1507
#>  [49]  11325.6158  12093.4312  12909.6240  13777.4151  14700.2315  15681.7202
#>  [55]  16725.7620  17836.4875  19018.2927  20275.8570  21614.1613  23038.5079
#>  [61]  24554.5415  26168.2716  27886.0961  29714.8268  31661.7165  33734.4879
#>  [67]  35941.3636  38291.0995  40793.0190  43457.0503  46293.7657  49314.4235
#>  [73]  52531.0128  55956.3009  59603.8843  63488.2423  67624.7948  72029.9634
#>  [79]  76721.2366  81717.2390  87037.8057  92704.0608  98738.5011 105165.0859
#>  [85] 112009.3315 119298.4132 127061.2726 135328.7329 144133.6212 153510.8988
#>  [91] 163497.7999 174133.9798 185461.6720 197525.8561 210374.4364 224058.4320
#>  [97] 238632.1795 254153.5487 270684.1725 288289.6915

df %>% 
  mutate(
    K = pmap_dbl(list(100, s, d, A, L, .3), K_way)
    # causing an error since the function is evaluated rowwise
  )
#> Error: Problem with `mutate()` column `K`.
#> i `K = pmap_dbl(list(100, s, d, A, L, 0.3), K_way)`.
#> x replacement has length zero

^{Created on 2021-09-18 by the reprex package (v2.0.1)}