xx7<-x7[x7[,5]>9,1]
xx7如下：
> xx7
[1] 04:41 04:56 05:11 05:26 05:41 05:56 06:11 06:34 06:26 06:41 07:00 06:56
[13] 07:23 07:12 07:32 07:27 07:42 07:57 08:24 08:11 08:26 08:41 09:02 08:57
[25] 09:12 09:27 09:47 09:42 09:57 10:12 10:27 10:44 10:42 11:04 10:58 11:13
[37] 11:35 11:27 11:42 12:01 12:05 12:08 12:09 11:58 12:13 12:15 12:17 12:13
[49] 13:13 13:28 13:43 13:43 13:58 14:13 14:39 14:28 14:43 14:58 15:13 15:37
[61] 15:28 15:43 15:43 15:58 16:23 16:14 16:34 16:29 16:44 17:01 16:59 17:14
[73] 17:42 17:29 17:49 17:44 18:00 18:06 17:59 18:14 18:29 18:52 18:44
134 Levels: 00:11 00:26 00:41 00:56 01:11 01:26 01:41 01:56 02:11 ... 23:47
xx7<-strtrim(xx7,2) ##抓取每个字符串的前两个字符
xx7<-xx7[!duplicated(xx7)] ##删除重复元素
x7<-read.table("xue17.txt")
xx8<-x8[x8[,5]>9,1]
xx8<-strtrim(xx8,2)
xx8<-xx8[!duplicated(xx8)]
xx9<-x9[x9[,5]>9,1]
xx9<-strtrim(xx9,2)
xx9<-xx9[!duplicated(xx9)]
xx9[match(xx8[match(xx7,xx8)],xx9)]->re ##注意match得到的是第二个变量中match到的地址
na.omit(re)[1:length(na.omit(re))]->ree ##删除NA值
ree
[1] "04" "05" "06" "10" "11" "12" "13" "14" "15" "16" "17" "18"
