---
title: "Introduction"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Introduction}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

For more details (and text), read [https://www.researchgate.net/publication/338549100_ESGtoolkit_a_tool_for_stochastic_simulation_v020](https://www.researchgate.net/publication/338549100_ESGtoolkit_a_tool_for_stochastic_simulation_v020). 

```{r}
library(esgtoolkit)
```

```{r fig.width=7.2}
# ESGtoolkit R Code Examples
# Source: ESGtoolkit documentation v0.2.0

# ============================================================================
# INSTALLATION
# ============================================================================

# ============================================================================
# BASIC SETUP FOR SIMSHOCKS EXAMPLES
# ============================================================================

# Number of simulations
nb <- 1000

# Number of risk factors
d <- 2

# Number of possible combinations of the risk factors (here : 1)
dd <- d*(d-1)/2

# Family : Gaussian copula
fam1 <- rep(1, dd)

# Correlation coefficients between the risk factors (d*(d-1)/2)
par0_1 <- 0.1
par0_2 <- -0.9

# ============================================================================
# SIMULATING SHOCKS WITH GAUSSIAN COPULA
# ============================================================================

set.seed(2)

# Simulation of shocks for the d risk factors
s0_par1 <- simshocks(n = nb, horizon = 4,
                     family = fam1, par = par0_1)

s0_par2 <- simshocks(n = nb, horizon = 4,
                     family = fam1, par = par0_2)

# ============================================================================
# CORRELATION TESTING
# ============================================================================

# Correlation test
esgcortest(s0_par1)

# Visualization of confidence intervals
(test <- esgcortest(s0_par2))
#par(mfrow=c(2, 1))
#esgplotbands(esgcortest(s0_par1))
#esgplotbands(test)

# ============================================================================
# CLAYTON COPULA EXAMPLES
# ============================================================================

# Family : Rotated Clayton (180 degrees)
fam2 <- 13
par0_3 <- 2

# Family : Rotated Clayton (90 degrees)
fam3 <- 23
par0_4 <- -2

# number of simulations
nb <- 200

# Simulation of shocks for the d risk factors
s0_par3 <- simshocks(n = nb, horizon = 4,
                     family = fam2, par = par0_3)

s0_par4 <- simshocks(n = nb, horizon = 4,
                     family = fam3, par = par0_4)

# Visualizing dependence between shocks
esgplotshocks(s0_par3, s0_par4)

# ============================================================================
# BATES MODEL (SVJD) - COMPLETE EXAMPLE
# ============================================================================

# Load required library for options pricing
#library(fOptions)

# ============================================================================
# BATES MODEL PARAMETERS
# ============================================================================

# Spot variance
V0 <- 0.1372

# mean-reversion speed
kappa <- 9.5110/100

# long-term variance
theta <- 0.0285

# volatility of volatility
volvol <- 0.8010/100

# Correlation between stoch. vol and prices
rho <- -0.5483

# Intensity of the Poisson process
lambda <- 0.3635

# mean and vol of the merton jumps diffusion
mu_J <- -0.2459
sigma_J <- 0.2547/100
m <- exp(mu_J + 0.5*(sigma_J^2)) - 1

# Initial stock price
S0 <- 4468.17

# Initial short rate
r0 <- 0.0357

# ============================================================================
# SIMULATION SETUP
# ============================================================================

n <- 300
horizon <- 1
freq <- "weekly"

# Simulation of shocks, with antithetic variates
shocks <- simshocks(n = n, horizon = horizon,
                    frequency = freq,
                    method = "anti",
                    family = 1, par = rho)

# ============================================================================
# VOLATILITY SIMULATION (CIR PROCESS)
# ============================================================================

# Vol simulation
sim_vol <- simdiff(n = n, horizon = horizon,
                   frequency = freq, model = "CIR", x0 = V0,
                   theta1 = kappa*theta, theta2 = kappa,
                   theta3 = volvol,
                   eps = shocks[[1]])

# Plotting the volatility (only for a low number of simulations)
esgplotts(sim_vol)

# ============================================================================
# ASSET PRICE SIMULATION (GBM WITH JUMPS)
# ============================================================================

# prices simulation
sim_price <- simdiff(n = n, horizon = horizon,
                     frequency = freq, model = "GBM", x0 = S0,
                     theta1 = r0 - lambda*m, theta2 = sim_vol,
                     lambda = lambda, mu_z = mu_J,
                     sigma_z = sigma_J,
                     eps = shocks[[2]])

# ============================================================================
# VISUALIZATION OF PRICE PATHS
# ============================================================================

# Plot asset price paths
#par(mfrow=c(2, 1))
#matplot(time(sim_price), sim_price, type = 'l',
#        main = "with matplot")
#esgplotbands(sim_price, main = "with esgplotbands", xlab = "time",
#             ylab = "values")

# ============================================================================
# MARTINGALE TESTING
# ============================================================================

# Discounted Monte Carlo price
print(as.numeric(esgmcprices(r0, sim_price, 2/52)))

# Initial price
print(S0)

# pct. difference
print(as.numeric((esgmcprices(r0, sim_price, 2/52)/S0 - 1)*100))

# convergence of the discounted price
esgmccv(r0, sim_price, 2/52,
        main = "Convergence towards the initial \n asset price")

# Statistical martingale test
martingaletest_sim_price <- esgmartingaletest(r = r0,
                                              X = sim_price,
                                              p0 = S0)

# Visualization of confidence intervals
esgplotbands(martingaletest_sim_price)
```

```{r eval=FALSE}
# ============================================================================
# OPTION PRICING EXAMPLE
# ============================================================================

# Option pricing parameters
# Strike
K <- 3400
Kts <- ts(matrix(K, nrow(sim_price), ncol(sim_price)),
          start = start(sim_price),
          deltat = deltat(sim_price),
          end = end(sim_price))

# Implied volatility
sigma_imp <- 0.6625

# Maturity
maturity <- 2/52

# payoff at maturity
payoff_ <- (sim_price - Kts)*(sim_price > Kts)
payoff <- window(payoff_,
                 start = deltat(sim_price),
                 deltat = deltat(sim_price),
                 names = paste0("Series ", 1:n))

# Monte Carlo price
print(as.numeric(esgmcprices(r = r0, X = payoff, maturity)))

# Convergence towards the option price
esgmccv(r = r0, X = payoff, maturity = maturity,
        main = "Convergence towards the call \n option price")
```