试图在我的Mac OS X上安装R包ggigraph时，遇到了依赖关系xml2的问题。
对于这个和其他包的用户来说，这似乎是一个相当常见的问题，所以在阅读了这里和其他地方的线程后，我确认了以下内容：
- RStudio，R及其所有软件包都是最新的
- libxml2安装在developer版本中，使用自制程序
- 我已经将libxml-2.0.pc从自制程序文件夹复制到/usr/local/lib/pkgconfig/
- 我已将/usr/local/lib/pkgconfig/添加到PATH和PKG_CONFIG_PATH
在安装过程中，我仍然收到以下错误消息。感谢您的帮助！
> install.packages("ggiraph")
Installing package into ‘/usr/local/lib/R/3.5/site-library’
(as ‘lib’ is unspecified)
also installing the dependency ‘xml2’
trying URL 'https://cran.rstudio.com/src/contrib/xml2_1.2.0.tar.gz'
Content type 'application/x-gzip' length 251614 bytes (245 KB)
==================================================
downloaded 245 KB
trying URL 'https://cran.rstudio.com/src/contrib/ggiraph_0.6.0.tar.gz'
Content type 'application/x-gzip' length 208710 bytes (203 KB)
==================================================
downloaded 203 KB
* installing *source* package ‘xml2’ ...
** package ‘xml2’ successfully unpacked and MD5 sums checked
Found pkg-config cflags and libs!
Using PKG_CFLAGS=-I/usr/include/libxml2
Using PKG_LIBS=-L/usr/lib -lxml2 -lz -lpthread -licucore -lm
------------------------- ANTICONF ERROR ---------------------------
Configuration failed because libxml-2.0 was not found. Try installing:
* deb: libxml2-dev (Debian, Ubuntu, etc)
* rpm: libxml2-devel (Fedora, CentOS, RHEL)
* csw: libxml2_dev (Solaris)
If libxml-2.0 is already installed, check that 'pkg-config' is in your
PATH and PKG_CONFIG_PATH contains a libxml-2.0.pc file. If pkg-config
is unavailable you can set INCLUDE_DIR and LIB_DIR manually via:
R CMD INSTALL --configure-vars='INCLUDE_DIR=... LIB_DIR=...'
--------------------------------------------------------------------
ERROR: configuration failed for package ‘xml2’
* removing ‘/usr/local/lib/R/3.5/site-library/xml2’
Warning in install.packages :
installation of package ‘xml2’ had non-zero exit status
ERROR: dependency ‘xml2’ is not available for package ‘ggiraph’
* removing ‘/usr/local/lib/R/3.5/site-library/ggiraph’
Warning in install.packages :
installation of package ‘ggiraph’ had non-zero exit status
这是我在使用Homebrew和libxml2的macOS上遇到的一个反复出现的问题。libxml2的includes位于编译器找不到的子目录/path/to/includes/libxml2/libxml/中。
我成功地在R中安装了xml2，做了两件事：
- 创建指向
[...]/include/libxml2/libxml的符号链接[...]/include/libxml - 将包含文件夹路径添加到
INCLUDE_DIR
在终端中执行点1。虽然文件路径在您的安装中可能有所不同，但我的mac上的shell命令是：
Bash > ln -s /usr/local/Cellar/libxml2/2.9.9_2/include/libxml2/libxml /usr/local/Cellar/libxml2/2.9.9_2/include/libxml`
在RStudio的R终端执行第2点。我mac上的命令是：
R > Sys.setenv(INCLUDE_DIR = paste("/usr/local/Cellar/libxml2/2.9.9_2/include", Sys.getenv("INCLUDE_DIR"), sep = ":"))`
然后安装xml2并最终安装ggiraph:
R > install.packages(c("xml2", "ggiraph"))