1. Load Required Libraries

# Load required libraries
library(tidyverse)
library(xts)
library(tidyverse)
library(xts)
library(lubridate)

2. Import Data and Format Time Series

# 1. Read raw CSV data from TEJ export
raw_data <- read_csv("C:/TejPro/TejPro/DataExport/tej_etf_data.csv")

# 3. Clean and rename columns
colnames(raw_data) <- c("Date", "0050 元大台灣50", "0052 富邦科技", "0056 元大高股息")

# 4. Format date column and sort chronologically (earliest first)х
formatted_df <- raw_data %>%
  mutate(Date = ymd(Date)) %>%
  filter(!is.na(Date)) %>%
  arrange(Date)

# 5. Convert to xts time series object
ts_data <- xts(formatted_df[, -1], order.by = formatted_df$Date)

# 6. Final result
head(ts_data)
##            0050 元大台灣50 0052 富邦科技 0056 元大高股息
## 2025-08-18         52.2403       29.1179         31.8394
## 2025-08-19         52.1423       29.0064         31.7578
## 2025-08-20         50.6721       28.0165         31.2952
## 2025-08-21         50.9661       28.3093         31.4857
## 2025-08-22         50.7211       28.0932         31.3859
## 2025-08-25         51.6522       28.8251         31.6943
## 3. Display Time Series Output
# Display the first few rows of the formatted time series
head(ts_data)
##            0050 元大台灣50 0052 富邦科技 0056 元大高股息
## 2025-08-18         52.2403       29.1179         31.8394
## 2025-08-19         52.1423       29.0064         31.7578
## 2025-08-20         50.6721       28.0165         31.2952
## 2025-08-21         50.9661       28.3093         31.4857
## 2025-08-22         50.7211       28.0932         31.3859
## 2025-08-25         51.6522       28.8251         31.6943