taylor rule estimation

library(readxl)
library(dplyr)

## 
## Attaching package: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

library(ggplot2)
library(lubridate)

## 
## Attaching package: 'lubridate'

## The following objects are masked from 'package:base':
## 
##     date, intersect, setdiff, union

dosya_adi_taylor <- "C:/Users/incet/Desktop/xu100_reaction/taylor rule estimation.xlsx"

taylor_raw <- read_excel(dosya_adi_taylor,col_types = "text") %>% 
  select(1:4) %>%
  setNames(c("Tarih_Raw", "CBRT_Raw", "Taylor_Raw", "Spread_Raw"))

taylor_df <- taylor_raw %>%
  mutate(
    
    Tarih_Metin = suppressWarnings(dmy(Tarih_Raw)),
    Tarih_Sayi = suppressWarnings(as.Date(as.numeric(Tarih_Raw), origin = "1899-12-30")),
    
  
    Tarih = coalesce(Tarih_Metin, Tarih_Sayi),
    
    CBRT = suppressWarnings(as.numeric(gsub(",", ".", as.character(CBRT_Raw)))),
    Taylor = suppressWarnings(as.numeric(gsub(",", ".", as.character(Taylor_Raw)))),
    Spread = suppressWarnings(as.numeric(gsub(",", ".", as.character(Spread_Raw))))
  ) %>%
  
  filter(!is.na(Tarih) & !is.na(CBRT))

ggplot(taylor_df, aes(x = Tarih)) +
  
  geom_area(aes(y = Spread, fill = "Makas (CBRT - Taylor)"), alpha = 0.3) +
  geom_line(aes(y = Taylor, color = "Taylor Kurali Tahmini"), linewidth = 1.2, lineend = "round", linejoin = "round") +
  geom_line(aes(y = CBRT, color = "TCMB Politika Faizi"), linewidth = 1.2, lineend = "round", linejoin = "round") +
  
  geom_hline(yintercept = 0, linetype = "dashed", color = "black", linewidth = 0.8) +
  
  scale_color_manual(name = "Gostergeler", values = c("TCMB Politika Faizi" = "#1A237E", "Taylor Kurali Tahmini" = "#E65100")) +
  scale_fill_manual(name = "Fark", values = c("Makas (CBRT - Taylor)" = "#D32F2F")) +
  
  theme_minimal() +
  labs(
    title = "TCMB Politika Faizi ve Taylor Kurali Kiyaslamasi",
    subtitle = "Uygulanan politika faizi ile teorik faiz orani arasindaki tarihsel makas",
    x = "Tarih",
    y = "Faiz Orani (%)"
  ) +
  scale_x_date(date_labels = "%b %Y", date_breaks = "3 months") +
  theme(
    plot.title = element_text(face = "bold", size = 14),
    plot.subtitle = element_text(color = "#555555", face = "italic", size = 12),
    axis.text.x = element_text(angle = 45, hjust = 1),
    panel.grid.major = element_line(color = "gray90", linewidth = 0.5),
    panel.grid.minor = element_blank(),
    
    legend.position = "bottom",
    legend.box = "vertical",
    legend.title = element_text(face = "bold", size = 10)
  )