这里有几个函数可以使用ExifTool为任何这些文件类型获取和设置 Exif 元数据。
要获取元数据:
getexif <- function(file, exiftool='exiftool.exe', opts=NULL,
intern=TRUE, simplify=FALSE) {
# file: the file to be updated
# exiftool: the path to the ExifTool binary
# opts: additional arguments to ExifTool (optional)
# intern: should a named vector of metadata be returned? (bool)
# simplify: if intern==TRUE, should the results be returned as a named
# vector (TRUE) or as a data.frame (FALSE)?
arg <- c(opts, normalizePath(file))
if(intern) {
exif <- system2(normalizePath(exiftool), args=arg, stdout=TRUE)
exif <- do.call(rbind, strsplit(exif, ' +: +', perl=T))
row.names(exif) <- exif[, 1]
exif[, 2, drop=simplify]
} else {
system2(normalizePath(exiftool), args=arg, stdout='')
}
}
设置元数据:
setexif <- function(file, ..., exiftool='exiftool.exe') {
# file: the file to be updated
# ...: metadata items
# exiftool: the path to the ExifTool binary
dots <- list(...)
exif <- sprintf('-%s="%s"', names(dots), dots)
system2(exiftool, args=c(exif, file))
}
这是一个例子
pdf(f <- tempfile(fileext='.pdf'))
plot(runif(10))
dev.off()
toolpath <- 'c:/software/exiftool(-k).exe'
setexif(f, title = "foo", subject='bar', author = "Me", exiftool=toolpath)
getexif(f, toolpath)
## [,1]
## ExifTool Version Number "9.64"
## File Name "file237c6f8d4dac.pdf"
## Directory "C:/Users/john/AppData/Local/Temp/RtmpSGqI6O"
## File Size "7.8 kB"
## File Modification Date/Time "2014:06:17 10:50:22+10:00"
## File Access Date/Time "2014:06:17 10:50:22+10:00"
## File Creation Date/Time "2014:06:17 10:50:20+10:00"
## File Permissions "rw-rw-rw-"
## File Type "PDF"
## MIME Type "application/pdf"
## PDF Version "1.4"
## Linearized "No"
## Create Date "2014:06:17 10:50:20"
## Modify Date "2014:06:17 10:50:20"
## Producer "R 3.1.0"
## Creator "R"
## Page Count "1"
## XMP Toolkit "Image::ExifTool 9.64"
## Subject "bar"
## Title "foo"
## Author "Me"