如何减去年份? [英] How to subtract years?

问题描述

我在R中有一个日期，例如:

I have a date in R, e.g.:

dt = as.Date('2010/03/17')

我想从这个日期开始减去2年，而不必担心leap年和此类问题，而得到as.Date('2010-03-17').

I would like to subtract 2 years from this date, without worrying about leap years and such issues, getting as.Date('2010-03-17').

我该怎么做?

推荐答案

最简单的方法是将其转换为POSIXlt并从年份中减去2.

The easiest thing to do is to convert it into POSIXlt and subtract 2 from the years slot.

> d <- as.POSIXlt(as.Date('2010/03/17'))
> d$year <- d$year-2
> as.Date(d)
[1] "2008-03-17"

请参阅以下相关问题:如何在R中减去天数?.

See this related question: How to subtract days in R?.

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