下面是创建一些测试数据的代码：

df <- data.frame(page_id = c(3,3,3,3,3), element_id = c(19, 22, 26, 31, 31), 
                 text = c("The Protected Percentage of your property value thats has been chosen is 0%", 
                          "The Arrangement Fee payable at complettion: £50.00", 
                          "Interest rate is fixed for the life of the period is: 5.40%", 
                          "The Benchmark rate that will be used to calculate any early repayment 2.08%", 
                          "The property value used in this scenario is 275,000.00"))

我有很多pdf文件，我想用正则表达式从中提取相同的信息 . 到目前为止，我已设法从1 pdf文件中提取所需的所有信息 . 下面是它的代码 - 评论：

library("textreadr")
library("pdftools")   
library("tidyverse")
library("tidytext")    
library("textreadr")
library("tm")

# read in the PDF file
Off_let_data <- read_pdf("50045400_K021_2017-V001_300547.pdf")

# read all pdf file from a folder
files <- list.files(pattern = "pdf$")[1]

# extract the account number from the first pdf file
acc_num <- str_extract(files, "^\\d+")

# The RegEx's used to extract the relevant information
protec_per_reg <- "Protected\\sP\\w+\\sof"
Arr_Fee_reg <- "^The\\sArrangement\\sF\\w+"
Fix_inter_reg <- "Fixed\\sI\\w+\\sR\\w+"
Bench_rate_reg <- "Benchmark\\sR\\w+\\sthat"

# create a df that only includes the rows which match the above RegEx
Off_let <- Off_let_data %>% filter(page_id == 3, str_detect(Off_let_data$text, protec_per_reg)|
                                     str_detect(Off_let_data$text, Arr_Fee_reg) | str_detect(Off_let_data$text, Fix_inter_reg) | 
                                     str_detect(Off_let_data$text, Bench_rate_reg))

# Now only extract the numbers from the above DF
off_let_num <- str_extract(Off_let$text, "\\d+\\.?\\d+")

# The first element is always a NA value - based on the structure of these PDF files
# replace the first element of this character vector with the below
off_let_num[is.na(off_let_num)] <- str_extract(Off_let$text, "\\d+%")[[1]] 
off_let_num

off_let_num 变量是一个向量，其中包含pdf文件中需要的4个元素 .

现在我想将所有这些步骤应用到包含许多pdf文件的文件夹中 . 所以，我已经设法将所有PDF文件读入单独的数据框 - 其代码如下：

# read all pdf files into a list
 file_list <- list.files(pattern = '*.pdf')

# Read in all the pdf files into seperate data frames
for (file_name in off_let) {
  assign(paste0("off","_",sub(".pdf","",file_name)), read_pdf(file_name))
}

我现在在我的工作目录中有许多数据框 . 我想在开始时将我应用于一个pdf文件的相同过程应用到以'off'开头的所有这些数据帧 .

我想要的方法是将初始进程转换为函数，然后调用此函数应用于以'off'开头的所有数据帧 . 结果应附加到数据框中，该数据框应包括从这些pdf文件中提取的所有元素（4） . 我不知道如何实现这一目标 . 请帮忙！

r function pdf