如何提取多个 XML 文件的文件属性并将它们与 XML 提取的数据组合（使用 R）

Question

I am fairly new to R and need some help to (extract and) combine file names and properties with data extracted from multiple xml files (about 200) which will should then be converted into a dataframe.

I am using the following script to select the xml files, extract the data and convert it into a dataframe (and is working without errors):

library(XML)
library(plyr)

# Select multiple xml files within directory
FileName <- list.files(pattern = "xml$",
                       ignore.case=TRUE,
                       full.names = FALSE)

# Create function to extract data
RI_ID <-function(FileName) {
  doc1 <- xmlParse(FileName) 
  doc <- xmlToDataFrame(doc1["//ObjectList[@ObjectType='pkg']/o"], )
} 

# Convert to dataframe
T1 <- ldply(FileName,RI_ID)

# Rename columns
names(T1)[names(T1) == "a"] <- "UniqueInstallationPackageID"
names(T1)[names(T1) == "b"] <- "PackageVersion_Latest"

# Convert to numeric
FieldToNumeric <- c("UniqueInstallationPackageID", "PackageVersion_Latest")
T1[,FieldToNumeric] <- lapply(T1[,FieldToNumeric], as.numeric)

I would like to (and need some help) to:

• extract the modified date of the xml file as it appear in windows explorer;
• include the file name as well as the modified date as part of the final dataframe.

I have reviewed the following two sources, but did not have any success in implementig them:

• http://datacornering.com/how-to-combine-files-with-r-and-add-filename-column/
• Read multiple xml files in R and combine the data

Due to a confidentiality agreement, I could not share an example of the xml file, but, if need be, can rename the nodes etc. and submit it. Thank you for your help.

Answer 1

Simply adjust RI_ID method to retrieve those two pieces of information (modified date/time with file.info and FileName variable) and bind those values into new columns of xml data frame. Below transform() allows adding columns to a data frame with comma separated assignments:

# Create function to extract data
RI_ID <-function(FileName) {
  doc <- xmlParse(FileName) 
  df <- transform(xmlToDataFrame(doc["//ObjectList[@ObjectType='pkg']/o"]),
                  file_name = FileName,
                  file_modified = file.info(FileName)$mtime)
}