Mia2018
试了一下确实不行, 试试这个,原理是先转为character vector, 然后用train的levels重新编码test集合的factor, 多出来的部分显示为NA,应该不会影响predict函数了
a = factor(c("a","b","c","d"))
b = factor(c("a","b","c","d","e", "f"))
b = as.character(b)
b = factor(b, levels = levels(a))
a
#> [1] a b c d
#> Levels: a b c d
b
#> [1] a b c d <NA> <NA>
#> Levels: a b c d
<sup>Created on 2018-10-11 by the reprex package (v0.2.1)</sup>