qoiqpwqr 发表于 2012-2-18 21:53 
数据导入应该是个data frame,而不是list,你是怎么导入的?
A data.frame is stored as a list. As stated in the help of mode() function,
Both mode and storage.mode return a character string giving the (storage) mode of the object — often the same — both relying on the output of typeof(x) ...
.
If one wants to check the logic type of data, the class() function should be used. See the following example: