如何从服务器下载图像，然后使用 R 将其上传到网站? [英] How do I download images from a server and then upload it to a website using R?

问题描述

好的，所以我在服务器上存储了大约 2 GB 的文件(图像和其他内容)(我现在使用的是 Cygwin，因为我在 Windows 上)，我想知道我是否能够获得所有将这些数据转换为 R，然后最终将其翻译到一个网站上，人们可以在该网站上查看/下载这些图像?

Okay, so I have approximately 2 GB worth of files (images and what not) stored on a server (I'm using Cygwin right now since I'm on Windows) and I was wondering if I was able to get all of this data into R and then eventually translate it onto a website where people can view/download those images?

我目前已经安装了 ssh 包并使用以下命令登录到我的服务器:

I currently have installed the ssh package and have logged into my server using:

ssh::ssh_connect("name_and_server_ip_here")

我已经能够成功连接，但是，我不太确定如何通过 R 定位服务器上的文件.我假设我会使用类似 scp_download 从服务器下载文件，但如前所述，我不太确定如何从服务器中找到文件，所以我无论如何都无法下载它们(目前)！

I've been able to successfully connect, however, I am not particular sure how to locate the files on the server through R. I assume I would use something like scp_download to download the files from the server, but as mentioned before, I am not particularly sure how to locate the files from the server, so I wouldn't be able to download them anyways (yet)!

任何形式的反馈和帮助将不胜感激！谢谢:)

Any sort of feedback and help would be appreciated! Thanks :)

推荐答案

您可以使用 ssh::ssh_exec_internal 和一些 shell 命令来查找"命令.

You can use ssh::ssh_exec_internal and some shell commands to "find" commands.

sess <- ssh::ssh_connect("r2@myth", passwd="...")
out <- ssh::ssh_exec_internal(sess, command = "find /home/r2/* -maxdepth 3 -type f -iname '*.log'")
str(out)
# List of 3
#  $ status: int 0
#  $ stdout: raw [1:70] 2f 68 6f 6d ...
#  $ stderr: raw(0) 

stdout/stderr 是raw(远程命令没有产生ascii 数据是可行的)，所以我们可以使用rawToChar 来转换.(如果您有非 ascii 数据，这可能不是控制台安全的，但它在这里，所以我会用它.)

The stdout/stderr are raw (it's feasible that the remote command did not produce ascii data), so we can use rawToChar to convert. (This may not be console-safe if you have non-ascii data, but it is here, so I'll go with it.)

rawToChar(out$stdout)
# [1] "/home/r2/logs/dns.log\n/home/r2/logs/ping.log\n/home/r2/logs/status.log\n"
remote_files <- strsplit(rawToChar(out$stdout), "\n")[[1]]
remote_files
# [1] "/home/r2/logs/dns.log"    "/home/r2/logs/ping.log"   "/home/r2/logs/status.log"

对于下载，scp_download没有矢量化，所以我们一次只能上传一个文件.

For downloading, scp_download is not vectorized, so we can only upload one file at a time.

for (rf in remote_files) ssh::scp_download(sess, files = rf, to = ".")
#    4339331 C:\Users\r2\.../dns.log
#   36741490 C:\Users\r2\.../ping.log
#   17619010 C:\Users\r2\.../status.log

对于上传，scp_upload 是矢量化的，因此我们可以一次性发送所有内容.我将创建一个新目录(仅用于此示例，并且不会完全弄乱我的远程服务器 :-)，然后上传它们.

For uploading, scp_upload is vectorized, so we can send all in one shot. I'll create a new directory (just for this example, and to not completely clutter my remote server :-), and then upload them.

ssh::ssh_exec_wait(sess, "mkdir '/home/r2/newlogs'")
# [1] 0
ssh::scp_upload(sess, files = basename(remote_files), to = "/home/r2/newlogs/")
# [100%] C:\Users\r2\...\dns.log
# [100%] C:\Users\r2\...\ping.log
# [100%] C:\Users\r2\...\status.log
# [1] "/home/r2/newlogs/"

(我觉得奇怪的是 scp_upload 是矢量化的，而 scp_download 不是.如果这是在 shell/终端上，那么每次调用 scp 需要连接、验证、复制，然后断开连接，有点低效；因为我们使用的是保存的 session，我相信(未经验证)有由于没有对 R 函数进行矢量化，效率损失很小……尽管矢量化它仍然真的很容易.)

(I find it odd that scp_upload is vectorized while scp_download is not. If this were on a shell/terminal, then each call to scp would need to connect, authenticate, copy, then disconnect, a bit inefficient; since we're using a saved session, I believe (unverified) that there is little efficiency lost due to not vectorizing the R function ... though it is still really easy to vectorize it.)

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