将"7-2014"转换为日期格式并在R中找到最小值 [英] converting `"7-2014"`into date format and finding minimum in R

问题描述

我在矢量date

> head(date)
[1] "7-2014"  "1-2018"  "11-2014" "7-2014"  "1-2018"  "1-2018" 

，并希望将其转换为日期并找到最小值.我按照此处

and want to convert it to date and find its minimum. I used as.Date as explained here

as.Date(date, "%m-%Y")

，但仅得到NA作为结果.为什么这不起作用?

but only get NA as result. Why is this not working?

我想在该栏中找到最短日期.如果您知道更好的方法，请告诉我:)

I want to find the minimum date in the column. If you know of a better approach, enlighten me :)

推荐答案

按日期需要一个月中的某天:

as.Date requires a day of the month:

date <- c("7-2014",  "1-2018",  "11-2014", "7-2014",  "1-2018",  "1-2018")
as.Date(paste0("1-", date), "%d-%m-%Y")
#> [1] "2014-07-01" "2018-01-01" "2014-11-01" "2014-07-01" "2018-01-01"
#> [6] "2018-01-01"

^{由 reprex软件包(v0.3.0)创建于2020-04-15 sup>}

^{Created on 2020-04-15 by the reprex package (v0.3.0)}

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