Question

我有一个大型csv文件，其中相关日期是分类的，并在一列中格式化如下：＆＃34;星期四，2012年1月21日04:59:00 -0000＆＃34;。我试图使用as.Date，但它似乎并没有起作用。对于工作日，日，月，年，可以创建多个列，但我很高兴在此时选择一列。有什么建议？

更新问题：每行在上述格式中都有不同的日期（工作日，日，月，年，小时，分钟，秒。我没有说清楚。如何转换列中的每个日期？

Answer 1

anytime包可以解析此而无需格式：

R> anytime("Thu, 21 Jan 2012 04:59:00 -0000")
[1] "2012-01-21 04:59:00 CST"
R>

它会返回POSIXct，您可以随意操作，或只是format()。它还有一个更简单的变体anydate()，它会返回一个Date对象。

Answer 2

我们可以使用

as.Date(str1, "%a, %d %b %Y")
#[1] "2012-01-21"

如果我们需要DateTime格式

v1 <- strptime(str1, '%a, %d %b %Y %H:%M:%S %z', tz = "UTC")
v1
#[1] "2012-01-21 04:59:00 UTC"

或使用lubridate

library(lubridate)
dmy_hms(str1)
#[1] "2012-01-21 04:59:00 UTC"

数据

str1 <- "Thu, 21 Jan 2012 04:59:00 -0000"

Answer 3

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Answer 4

如果您真的想要在组件中进行分离，那么请从Dirk的强大建议开始，然后转置as.POSIXlt的输出：

library(anytime)
times <- c("2004-03-21 12:45:33.123456", # example from ?anytime
          "2004/03/21 12:45:33.123456",
          "20040321 124533.123456",
          "03/21/2004 12:45:33.123456",
          "03-21-2004 12:45:33.123456",
          "2004-03-21",
          "20040321",
          "03/21/2004",
          "03-21-2004",
          "20010101")
    t( sapply( anytime::anytime(times), 
                     function(x) unlist( as.POSIXlt(x)) ) )

      sec                min  hour mday mon year  wday yday  isdst
 [1,] "33.1234560012817" "45" "12" "21" "2" "104" "0"  "80"  "0"  
 [2,] "33.1234560012817" "45" "12" "21" "2" "104" "0"  "80"  "0"  
 [3,] "33.1234560012817" "45" "12" "21" "2" "104" "0"  "80"  "0"  
 [4,] "33.1234560012817" "45" "12" "21" "2" "104" "0"  "80"  "0"  
 [5,] "33.1234560012817" "45" "12" "21" "2" "104" "0"  "80"  "0"  
 [6,] "0"                "0"  "0"  "21" "2" "104" "0"  "80"  "0"  
 [7,] "0"                "0"  "0"  "21" "2" "104" "0"  "80"  "0"  
 [8,] "0"                "0"  "0"  "21" "2" "104" "0"  "80"  "0"  
 [9,] "0"                "0"  "0"  "21" "2" "104" "0"  "80"  "0"  
[10,] "0"                "0"  "0"  "1"  "9" "101" "1"  "273" "1"  
      zone  gmtoff  
 [1,] "PST" "-28800"
 [2,] "PST" "-28800"
 [3,] "PST" "-28800"
 [4,] "PST" "-28800"
 [5,] "PST" "-28800"
 [6,] "PST" "-28800"
 [7,] "PST" "-28800"
 [8,] "PST" "-28800"
 [9,] "PST" "-28800"
[10,] "PDT" "-25200"

在R中转换日期

4 个答案:

数据