如果使用colClasses
参数来读取CSV文件中跨越两个“列”的数据到R中,则无法完成此操作。相反,需将日期和时间列加载并处理为单个POSIXlt
变量:
dat <- read.csv(textConnection("date,time,val1,val2
20090503,0:05:12,107.25,1
20090503,0:05:17,108.25,20
20090503,0:07:45,110.25,5
20090503,0:07:56,106.25,5"))
dat <- within(dat, Datetime <- as.POSIXlt(paste(date, time),
format = "%Y%m%d %H:%M:%S"))
[我猜想这是年月日?如果不是,请使用"%Y%d%m %H:%M:%S"
]
这样得到:
> head(dat)
date time val1 val2 Datetime
1 20090503 0:05:12 107.25 1 2009-05-03 00:05:12
2 20090503 0:05:17 108.25 20 2009-05-03 00:05:17
3 20090503 0:07:45 110.25 5 2009-05-03 00:07:45
4 20090503 0:07:56 106.25 5 2009-05-03 00:07:56
> str(dat)
'data.frame': 4 obs. of 5 variables:
$ date : int 20090503 20090503 20090503 20090503
$ time : Factor w/ 4 levels "0:05:12","0:05:17",..: 1 2 3 4
$ val1 : num 107 108 110 106
$ val2 : int 1 20 5 5
$ Datetime: POSIXlt, format: "2009-05-03 00:05:12" "2009-05-03 00:05:17" ...
如果您愿意,现在可以删除日期
和时间
:
> dat <- dat[, -(1:2)]
> head(dat)
val1 val2 Datetime
1 107.25 1 2009-05-03 00:05:12
2 108.25 20 2009-05-03 00:05:17
3 110.25 5 2009-05-03 00:07:45
4 106.25 5 2009-05-03 00:07:56