How to extract and manipulate web data in the R programming language?

In R language, you can use certain packages to scrape and manipulate web data, commonly used packages include rvest, httr, XML, etc. Below is a simple example code demonstrating how to scrape data from a webpage.

# 安装和加载需要的包
install.packages("rvest")
library(rvest)

# 抓取网页数据
url <- "https://www.example.com"
webpage <- read_html(url)

# 提取数据
data <- webpage %>%
  html_nodes("css选择器") %>%
  html_text()

# 处理数据
# 例如，将数据转换成数据框
df <- data.frame(data)

# 输出结果
print(df)

In the code above, the rvest package is first installed and loaded. Then, the read_html() function is used to scrape data from a web page. Next, the html_nodes() function is used to select the desired data, and finally the data is processed and the results are outputted. Depending on the specific requirements, different methods and functions can be used to handle web page data.