Forma Tradicional

library(readxl)
library(forecast)
Luis_Fernando_Lagos_Alas_IVAE_SLV_C <- read_excel("~/Econometria Guia Practica Bases de Datos/Luis Fernando Lagos Alas - IVAE_SLV_C.xlsx", col_types=c("skip", "numeric"), skip=5)
IVAEs<- ts(data = Luis_Fernando_Lagos_Alas_IVAE_SLV_C, start = c(2009, 1), frequency = 12)
IVAEs%>% 
  autoplot(main = "IVAE, El Salvador 2009-2021(marzo)", xlab = "Años/Meses", ylab = "Indice")

mx12 <- ma(IVAEs, 12, centre = T)
autoplot(IVAEs,main = "IVAE, El Salvador 2009-2021(marzo)", xlab = "Años/Meses", ylab = "Indice")+ autolayer(mx12,series = "Tt")

library(magrittr)
yt <- IVAEs
tt <- mx12
sI <- yt - tt

st <- tapply(sI, cycle(sI), mean, na.rm = T)
st <- st - sum(st) / 12 
st <-rep(st, len = length(yt)) %>% ts(start = c(2009, 1), frequency = 12) 
autoplot(st, main = "Factores Estacionales", xlab = "Años/Meses", ylab = "Factor Estacional")

it<-yt-tt-st
autoplot(it, main = "Componente Irregular", xlab = "Años/Meses", ylab = "it")

desadix<-decompose(IVAEs,type = "additive")
autoplot(desadix,main="Descomposición Aditiva",xlab="Años/Meses")

library(tsibble)
library(feasts)
library(ggplot2)
yt %>% as_tsibble() %>%
  model(classical_decomposition(value, type = "additive")) %>% components() %>% autoplot() + labs(title = "Descomposición Clásica Aditiva, IVAE")+xlab("Años/Meses")

## Modelo Multiplicativo

TT<- ma(IVAEs, 12, centre = TRUE)
autoplot(TT,main = "Componente Tendencia [Ciclo]", xlab = "Años/Meses",ylab = "tt")

SI<-yt/tt
st <- tapply(SI, cycle(SI), mean, na.rm = TRUE)
st <- st*12/sum(st) 
st <- rep(st, len = length(yt)) %>% ts(start = c(2009, 1), frequency = 12) 
autoplot(st, main = "Factores Estacionales", xlab = "Años/Meses", ylab = "Factor Estacional") 

it<-yt/(tt*st)
autoplot(it, main = "Componente Irregular", xlab = "Años/Meses", ylab = "It")

Desmul<-decompose(IVAEs,type = "multiplicative")
autoplot(Desmul,main="Descomposición Multiplicativa",xlab="Años/Meses")

yt %>% as_tsibble() %>% model(classical_decomposition(value, type = "multiplicative")) %>% components() %>% autoplot() + labs(title = "Descomposición Clásica Multiplicativa, IVAE")+xlab("Años/Meses")