安装R包时遇到如下错误：
> install.packages("D:/R包/npmc_1.0.tar.gz", repos = NULL, type = "source")Installing package into ‘C:/Users/penny/Documents/R/win-library/3.5’(as ‘lib’ is unspecified)* installing *source* package 'npmc' ...ERROR: a 'NAMESPACE' file is required* removing 'C:/Users/penny/Documents/R/win-library/3.5/npmc'In R CMD INSTALLWarning in install.packages :  installation of package ‘D:/R包/npmc_1.0.tar.gz’ had non-zero exit status

请问该如何解决？