Question

我是R的新手，我正在寻找一种方法来提取我的数据帧中的小时分钟和借调。我尝试了一些库，但没有成功。

这是我目前的代码：

daily_data = read.csv("/Us/eco.csv", header=TRUE, stringsAsFactors=FALSE)

daily_hour= daily_data$time

daily_hour

以下是我约会的日期：

 [1] "2016-08-19 17:45:19" "2016-08-19 17:45:19" "2016-08-19 17:45:19" "2016-08-19 17:45:19"
   [5] "2016-08-19 18:59:19" "2016-08-19 18:59:19" "2016-08-19 18:59:19" "2016-08-19 18:59:19"
   [9] "2016-08-19 18:59:19" "2016-08-19 18:59:19" "2016-08-19 18:59:19" "2016-08-19 18:59:19"
  [13] "2016-08-19 19:27:07" "2016-08-19 19:27:07" "2016-08-19 19:27:07" "2016-08-19 19:27:07"
  [17] "2016-08-19 19:27:07" "2016-08-19 19:27:07" "2016-08-19 23:33:46" "2016-08-19 23:33:46"
  [21] "2016-08-19 23:33:46" "2016-08-19 23:33:46" "2016-08-20 07:13:32" "2016-08-20 07:13:32"
  [25] "2016-08-20 07:13:32" "2016-08-20 07:13:32" "2016-08-20 08:52:12" "2016-08-20 08:52:12"
  [29] "2016-08-20 08:52:12" "2016-08-20 08:52:12" "2016-08-20 10:06:53" "2016-08-20 10:06:53"
  [33] "2016-08-20 10:06:53" "2016-08-20 10:06:53" "2016-08-20 10:06:56" "2016-08-20 10:06:56"

Answer 1

hms <- sub('\\d+-\\d+-\\d+ ', '', daily_hour)会将字符串的小时：分钟：秒部分提取为字符串。如果您需要将这些变量分成其他变量，则有两种选择。

# Option 1
hours <- sub(':\\d+:\\d+', '', hms)
mins <- sub('\\d+:(\\d+):\\d+', '\\1', hms)
secs <- sub('\\d+:\\d+:', '', hms)

# Option 2
daily_hour <- as.POSIXct(daily_hour)
hours <- as.numeric(format(daily_hour, "%H"))
mins <- as.numeric(format(daily_hour, "%M"))
secs <- as.numeric(format(daily_hour, "%S"))

Answer 2

假设您的数据：

daily_hour = data.frame(time = c("2016-08-19 17:45:19", "2016-08-19 17:45:36"))

然后将其拆分为sep = " "并获取列表的第二个元素，您将获得一个hh：mm：ss的向量：

sapply(daily_hour$time, function(x) strsplit(as.character(x), " ")[[1]][2])

Answer 3

如果您的日期格式一致，您还可以使用substr。

substr(daily_hour, 12, 19)

substr("2016-08-19 17:45:19", 12, 19)
[1] "17:45:19"

在数据帧上提取小时

3 个答案: