Created
February 10, 2019 07:38
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Deterministic multistage Beverton-Holt model using nested for loops in R
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years = 30 | |
prop_female = 0.5 | |
egg_surv = 0.6 | |
fecundity = c(0, 0, 200, 400, 800) | |
survival = c(0.2, 0.4, 0.6, 0.8, 0) | |
capacity = c(1e6, 1e5, 1e4, 1e3, 1e2) | |
beverton_holt <- function(N, p, c){ | |
N / ((1/p) + (N/c)) | |
} | |
results = matrix(data = 0, nrow = years, ncol = length(fecundity)) | |
results[1,] = 10 | |
for (i in 1:(nrow(results) - 1)){ | |
for (j in 1:(ncol(results))){ | |
N = results[i,j] | |
fec_age_j = fecundity[j] | |
surv_age_j = survival[j] | |
# spawning | |
if (fec_age_j > 0){ | |
spawn_age_j = N * prop_female | |
results[i+1, 1] = results[i+1, 1] + beverton_holt(spawn_age_j, fec_age_j * egg_surv, capacity[1] - results[i+1, 1]) | |
} | |
# survival | |
if (surv_age_j > 0){ | |
results[i+1, j+1] = results[i+1, j+1] + beverton_holt(N, surv_age_j, capacity[j+1] - results[i+1, j+1]) | |
} | |
} | |
} | |
results |
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