Question

我正在尝试计算多个pdf文件中关键字的数量。

library(tm)
library(pdftools)

files <- list.files(pattern = "pdf$")
Rpdf <- readPDF(control = list(text = "-layout"))
corp <- Corpus(URISource(files), readerControl = list(reader = Rpdf))

words <- c("example", "keyword", "test")
dt <- DocumentTermMatrix(corp, control=list(dictionary=words))

运行代码时，我总是会遇到此错误：

PDF error: May not be a PDF file (continuing anyway)
PDF error (3): Illegal character <21> in hex string
PDF error (5): Illegal character <4f> in hex string
PDF error (7): Illegal character <54> in hex string
PDF error (8): Illegal character <59> in hex string
PDF error (9): Illegal character <50> in hex string
PDF error: Couldn't find trailer dictionary
PDF error: Couldn't find trailer dictionary
PDF error: Couldn't read xref table
Error in poppler_pdf_text(loadfile(pdf), opw, upw) : PDF parsing failure.
In addition: There were 12 warnings (use warnings() to see them)

如果您有任何建议，请告诉我。谢谢！

Answer 1

我想您的pdf格式为二进制文件，因此应该作为二进制文件下载/读取。我在使用download.file下载pdf文件时遇到了类似的问题。下载它们后，我无法使用pdftools从pdf挖掘信息。我发现我的pdf包含二进制文件和不完整的BC，但我没有以正确的格式下载它们（尝试使用任何pdf阅读器，打开pdf时应该说它已损坏）。使用Windows作为操作系统，我向mode="wb"添加了download.file，以确保它以正确的格式存储它们。然后，我可以从pdftools上运行功能，而不会收到该错误消息。希望能有所帮助。从这样的问题中得到了一个主意：Problems with Downloading pdf file using R

与您的错误消息相同：

pdf_toc(example_path)
PDF error (1151926): Illegal character <3a> in hex string
PDF error (1151929): Illegal character <73> in hex string
[...omitted for brevity...]
PDF error (1152006): Illegal character <22> in hex string
PDF error: Couldn't find trailer dictionary
PDF error: Couldn't read xref table
Error in poppler_pdf_toc(loadfile(pdf), opw, upw) : PDF parsing failure.

R脚本-PDF错误：十六进制字符串中的字符非法；当我搜索关键字时

1 个答案: