# Create two multi-page pdfs and add bookmarks to themf_a<-tempfile(fileext =".pdf")pdf(f_a,title ="Document A",onefile =TRUE)grid::grid.text("Document A: First Page")grid::grid.newpage()grid::grid.text("Document A: Second Page")dev.off()|>invisible()f_b<-tempfile(fileext =".pdf")pdf(f_b,title ="Document B",onefile =TRUE)grid::grid.text("Document B: First Page")grid::grid.newpage()grid::grid.text("Document B: Second Page")dev.off()|>invisible()bm<-data.frame(title =c("First Page","Second Page"),page =c(1,2))set_bookmarks(bm, f_a)set_bookmarks(bm, f_b)# Concatenate pdfs to a single pdf and add their concatenated bookmarks to itfiles<-c(f_a, f_b)f_cat<-tempfile(fileext =".pdf")cat_pages(files, f_cat)cat_bookmarks(get_bookmarks(files),method ="title")|>set_bookmarks(f_cat)print(get_bookmarks(f_cat)[[1]])

##         title page level count open color fontface## 1  Document A    1     1    NA   NA  <NA>     <NA>## 2  First Page    1     2    NA   NA  <NA>     <NA>## 3 Second Page    2     2    NA   NA  <NA>     <NA>## 4  Document B    3     1    NA   NA  <NA>     <NA>## 5  First Page    3     2    NA   NA  <NA>     <NA>## 6 Second Page    4     2    NA   NA  <NA>     <NA>

Limitations bybackend

Known limitations:

• get_bookmarks_pdftk() doesn’t report information aboutbookmarks color, font face, and whether the bookmarks should start openor closed.
• get_bookmarks_pdftools()’s doesn’t report informationabout bookmarks pages, color, font face, and whether the bookmarks
• get_docinfo_exiftool() “widens” datetimes to secondprecision. An hour-only UTC offset will be “widened” to minuteprecision.
• get_docinfo_pdftools()’s datetimes may not accuratelyreflect the embedded datetimes.
• set_bookmarks_gs() supports most bookmarks featuresincluding color and font face but only action supported is to view aparticular page.
• set_bookmarks_pdftk() only supports setting the title,page number, and level of bookmarks.
• set_docinfo_pdftk() may not handle entries withnewlines in them.
• All of theset_docinfo() methods currently do notsupport arbitrary info dictionary entries.
• As a side effectset_docinfo_gs() seems to also updateany matching XPN metadata whileset_docinfo_exiftool() andset_docinfo_pdftk() don’t update any previously setmatching XPN metadata. Some pdf viewers will preferentially use thepreviously set document title from XPN metadata if it exists instead ofusing the title set in documentation info dictionary entry. Consideralso manually setting this XPN metadata usingset_xmp()
• Old metadata information is usually not deleted from the files bythese operations (i.e. these operations are often theoreticallyreversible). If deleting the old metadata is important one may want toconsider callingqpdf::pdf_compress(input, linearize = TRUE) at theend.

External links

Metadata links

• basicpdfmark features (Adobe) documents “Documentation info dictionary”metadata and “Bookmarks”
• IPTCPhoto Metadata Standard (IPTC) is a popular XMP metadata standardfor photos
• Quickguide to IPTC Photo Metadata on Google Images (IPTC) describes thesubset of the IPTC Photo Metadata Standard used by Google Photos to listphoto credits and license information
• xmp-docs(Adobe) describes some common XMP tags
• XMP(Creative Commons) describes a standard for using XMP to embed CreativeCommons license information
• XMP tags(exiftool) is a fairly comprehensive list of XMP tags

Related software

Note most of the R packages listed below are focused ongetting metadata rather thansettingmetadata and/or only provide low-level wrappers around the relevantcommand-line tools. Please feel free toopen apull request to add any missing relevant R packages.

exempi

• exempi

exiftool

• {exifr} providesa high-level wrapper to read metadata as well as a low-level wrapperaround theexiftool command-line tool. Can downloadexiftool.
• {exiftoolr}provides high-level wrapper to read metadata as well as a low-levelwrapper around theexiftool command-line tool. Can downloadexiftool.
• exiftool

exiv2

• {exiv} read and write‘Exif’, ‘ID3v1’ and ‘ID3v2’ image/media tags
• exiv2

other exif tools

• {exif} reads EXIFfrom jpeg images
• {magick} hasimage_attributes() which reads EXIF image tags.

ghostscript

• {tools} hasfind_gs_cmd() to find aGhostScript executable in a cross-platform way.
• ghostscript

poppler

• {pdftools}
• {Rpoppler}
• poppler

qpdf

• {qpdf}
• qpdf

pdftk

• {animation} haspdftk(), a low-level wrapper around thepdftkcommand-line tool.
• pdftk
• pdftk-java

tabula

• {tabulizer}
• tabula-java

xpdf

• xpdf’spdfinfo tool