将季度/年格式转换为日期 [英] Convert quarter/year format to a date

问题描述

我创建了一个将四分之一年格式的矢量强制转换为日期矢量的函数。

I created a function that coerce a vector of quarters-years format to a vector of dates.

.quarter_to_date(c("Q1/13","Q2/14"))
[1] "2013-03-01" "2014-06-01"

这是我函数的代码。

.quarter_to_date <-
  function(x){
    ll <- strsplit(gsub('Q([0-9])[/]([0-9]+)','\\1,\\2',x),',')

    res <- lapply(ll,function(x){
      m <- as.numeric(x[1])*3
      m <- ifelse(nchar(m)==1,paste0('0',m),as.character(m))
      as.Date(paste(x[2],m,'01',sep='-'),format='%y-%m-%d')

    })
    do.call(c,res)
  }

我的函数工作正常，但看起来又长又有点复杂。我认为应该在其他软件包中完成此操作（例如 lubridate ），但是我找不到它。有人可以帮我简化这段代码吗？

My function works fine but it looks long and a little bit complicated. I think that this should be already done in other packages( lubridate for example) But I can't find it. Can someone help me to simplify this code please?

推荐答案

1）动物园程序包中有一个 yearqtr 类。转换为该值，然后转换为日期 类：

1) The zoo package has a "yearqtr" class. Convert to that and then to "Date" class:

library(zoo)
x <- c("Q1/13","Q2/14")

as.Date(as.yearqtr(x, format = "Q%q/%y"))
## [1] "2013-01-01" "2014-04-01"

2）这也可以获取月份的最后一天而不是第一天：

2) This also works to get the last day of the month instead of the first:

as.Date(as.yearqtr(x, format = "Q%q/%y"), frac = 1)
## [1] "2013-03-31" "2014-06-30"

3）也请考虑不要转换为日期 类，而直接使用 yearqtr 类：

3) Also consider not converting to "Date" class at all and just using "yearqtr" class directly:

as.yearqtr(x, format = "Q%q/%y")
## [1] "2013 Q1" "2014 Q2"

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