• 因子转字符

  df<-data.frame(Gender = c("F", "F", "M","M","F"), 
                 Score  = c(80, 70, 65, 85, 95),
                 Type = c("A","B","C","B","B"))
  df[sapply(df, is.character)] <- lapply(df[sapply(df, is.character)], 
                                         as.factor)

• 字符转因子

  df[sapply(df, is.factor)] <- lapply(df[sapply(df, is.factor)], 
                                         as.character)

options(warn = -1) #关闭警告信息
options(warn = 0) #打开警告信息