基于年份生成年龄变量的思考 [英] Thoughts on Generating an Age Variable Based on Years

问题描述

我多年来一直在尝试创建一个虚拟变量.目前，我的数据对于每个观察都有一个birth_date 和一个program start_date.我已经能够创建一个以天为单位测量个人年龄的变量，但我实际寻找的是一个变量:age_join_date 告诉我以下内容:

I am trying to create a dummy variable for years. Currently, my data has a birth_date and a program start_date for each observation. I have been able to create a variable measuring an individual's age in days, but what I am actually looking for is a variable: age_join_date that tells me the following:

Individual birth_date    start_date  age_at_join_date
A          1990-12-31    2010-12-31  20 yrs old

B          1990-12-31    2011-12-31  21 yrs old

基本上我关心的是他们加入计划时的年龄，而不是他们的实际年龄.

Essentially what I care about is one's age at the time they joined the program, rather than their actual age.

推荐答案

你的问题我不是很清楚，但我认为你可以使用一些 lubridate 函数来达到预期的结果，作为间隔运算符 %--% 和 years 各自的间隔.

You question was not really clear to me, but I think you can achieve the expected result using some lubridate functions, as the interval operator %--% and years of the respective interval.

library(lubridate)
library(dplyr)

tibble::tribble(
  ~Individual,  ~birth_date,  ~start_date,
  "A", "31/12/1990", "31/12/2010",
  "B", "31/12/1990", "31/12/2011"
) %>% 
  mutate_at(vars(ends_with("date")), dmy) %>%  #just making date columns as date
  mutate(age_at_join_date = birth_date %--% start_date/years(1))

#> # A tibble: 2 x 4
#>   Individual birth_date start_date age_at_join_date
#>   <chr>      <date>     <date>                <dbl>
#> 1 A          1990-12-31 2010-12-31               20
#> 2 B          1990-12-31 2011-12-31               21

^{由 reprex 包 (v0.3.0) 于 2020 年 2 月 12 日创建}

^{Created on 2020-02-12 by the reprex package (v0.3.0)}

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