R语言：In `[<-.factor`(`*tmp*`, thisvar, value = " ") : invalid factor level, NA generat

使用命令时出现报错：

count3 = read.table("summary.txt",header=T,sep="\t")
count3[is.na(count3)] <- "rs111"

In `[<-.factor`(`*tmp*`, thisvar, value = "rs111") :
  invalid factor level, NA generated

报错原因

"rs111"是character，而我要替换的NA属性为factor，factor属性的NA不能替换为character属性的"rs111"

解决办法

加上stringsAsFactors = FALSE参数：

count3 = read.table("summary.txt",header=T,sep="\t", stringsAsFactors = FALSE)
count3[is.na(count3)] <- "rs111"