R:使Ryacas包在Windows上运行时出现问题

Question

我正在尝试使用R中的Ryacas包。下面是正在发生的事情：

> install.packages("Ryacas")
--- Please select a CRAN mirror for use in this session ---
trying URL 'http://www.stats.bris.ac.uk/R/bin/windows/contrib/2.14/Ryacas_0.2-11.zip'
Content type 'application/zip' length 263424 bytes (257 Kb)
opened URL
downloaded 257 Kb

package ‘Ryacas’ successfully unpacked and MD5 sums checked

The downloaded packages are in
    C:\Documents and Settings\yogcal\Local Settings\Temp\RtmpKeuu7m\downloaded_packages

然后我尝试加载Ryacas

> library(Ryacas)
Loading required package: XML
C:\Program Files\R\R-2.14.1\library\Ryacas\yacdir\yacas.exe 
   or C:\Program Files\R\R-2.14.1\library\Ryacas\yacdir\scripts.dat 
 not found.
Run yacasInstall() without arguments to install yacas.

然后我运行yacasInstall()

> yacasInstall()
trying URL 'http://ryacas.googlecode.com/files/yacas-1.0.63.zip'
Content type 'application/x-zip' length 746009 bytes (728 Kb)
opened URL
downloaded 728 Kb

然后，当我尝试一个示例时：

> library(Ryacas)
> yacas("TeXForm(3 * x^2/(2 * (x + 1)) - (x^3) * 2/(2 * (x + 1))^2)", 
+  retclass = "unquote")
[1] "Starting Yacas!"
Error in socketConnection(host = "127.0.0.1", port = 9734, server = FALSE,  : 
  cannot open the connection
In addition: Warning message:
In socketConnection(host = "127.0.0.1", port = 9734, server = FALSE,  :
  127.0.0.1:9734 cannot be opened
> 

这里出了什么问题？

非常感谢。

Answer 1

两种可能性: 1) Yacas从来没有开始过。(R不会为您加载Yacas。) 2)连接被阻塞。假设您从操作系统启动了Yacas，那么您需要使用安全管理工具打开该端口。这不是R问题，而是操作系统/防火墙问题。

关于需要从开始菜单启动Yacas，我可能是错的。这是以下代码：

runYacas()
### You should not need to type any of what follows. Just use the command above.
runYacas <- function(method = "system", yacas.args = "", yacas.init = "") {
   cmd <- yacasInvokeString(method = method, yacas.args = yacas.args, yacas.init = yacas.init)
   if (.Platform$OS.type == "windows") 
      system(cmd, wait = FALSE, invisible = FALSE)
   else system(cmd, wait = FALSE)
}

因为它似乎在调用系统，所以我会在R提示符下尝试。

Answer 2

解决问题的一种方法是确保端口是打开的：

1)点击Windows Start

2)点击All Programs

3)点击Accessories

4)点击Command Prompt，打开DOS窗口

5)输入cd C:\Program Files\yacas\winrel，将目录更改为yacas.exe所在的目录(可能是C:\Program Files\yacas\winrel

6)通过输入yacas --server 9734启动服务器上的yacas

7) Yacas应该给你以下的反馈Accepting requests from port 9734

如果到目前为止一切正常，那么yacas正在运行并准备好对话。现在，你可以运行你的R代码了。如果它不工作，那么您的yacas就有问题了。