摘要：### subset 函数 airquality <- airquality #选取Temp大于80的行，保留Ozone,temp两列 subset(airquality, Temp > 80, select = c(Ozone, Temp)) #选取day等于1的行，删去temp列 subset( 阅读全文

摘要：ifelse returns a value with the same shape as test which is filled with elements selected from either yes or no depending on whether the element of te 阅读全文

摘要：输入top 查看后台 找到自己所属编号 输入 kill -9 编号 阅读全文