[英]Why do I need to use mode = wb with download.file() for this .rds file?
I was getting hung up on Shiny Apps Tutorial Lesson 5 because I was unable to open the counties.rds
file. 我无法进入Shiny Apps教程第5课,因为无法打开counties.rds
文件。 readRDS()
threw: error reading from connection
. readRDS()
抛出: error reading from connection
。
I figured out I could open the .rds
fine if I downloaded it with download.file(URL, dest, mode = "wb")
or simply used my browser to download the file to my local directory. 我.rds
如果使用download.file(URL, dest, mode = "wb")
下载该.rds
文件,或者只是使用我的浏览器将该文件下载到本地目录download.file(URL, dest, mode = "wb")
则可以打开.rds
。
Outstanding Question: Why does the counties.rds
file not open properly if I use download.file()
without setting mode = "wb"
? 悬而未决的问题:如果在没有设置mode = "wb"
情况mode = "wb"
使用download.file()
为什么counties.rds
文件无法正确打开? I expect the answer will be something obvious like: "Duh, counties.rds
is a binary file." 我希望答案将是显而易见的:““, counties.rds
是一个二进制文件。” However, before I try to answer my own question, I'd like confirmation from someone with more experience. 但是,在尝试回答自己的问题之前,我想请经验丰富的人确认。
Repro steps: 复制步骤:
download.file("http://shiny.rstudio.com/tutorial/lesson5/census-app/data/counties.rds",
"counties.rds")
counties <- readRDS("counties.rds")
Error in readRDS("counties.rds") : error reading from connection
Resolution: Download via browser or use binary mode ( wb
). 解决方法:通过浏览器下载或使用二进制模式( wb
)。
download.file("http://shiny.rstudio.com/tutorial/lesson5/census-app/data/counties.rds",
"counties.rds", mode = "wb")
counties <- readRDS("counties.rds") # Success!
My suggestion is to always specify 'mode' regardless and that it pretty safe to always use mode="wb". 我的建议是始终指定“ mode”,并且始终使用mode =“ wb”非常安全。 I argue it the latter should be the default and that the automatic recognition by file extension is faulty and should not be relied upon, cf. 我认为后者应为默认值,并且通过文件扩展名自动识别是错误的,不应依赖于此。 https://stat.ethz.ch/pipermail/r-devel/2012-August/064739.html https://stat.ethz.ch/pipermail/r-devel/2012-August/064739.html
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