生成了一个维数相同的数据实验了一下, 无法重现问题.
试试不在SAS里导出csv再用R读, 而是用foreign包中提供的相关函数进行导出和读入.
以下来自R Data Import/Export:
Function read.xport reads a file in SAS Transport (XPORT) format and return a list of data frames. If SAS is available on your system, function read.ssd can be used to create and run a SAS script that saves a SAS permanent dataset (.ssd or .sas7bdat) in Transport format. It then calls read.xport to read the resulting file. (Package Hmisc has a similar function sas.get, also running SAS.)