问题
Is it possible to format the following number to Year-Month I entries as follows:
1402 1401 1312
Meaning February 2014. January 2014 and December 2013.
I tried:
date <- 1402
date <- as.Date(as.character(date), format = "%y%m")
But I get an NA as an output.
回答1:
The zoo package has a "yearmon" class that directly handles year/month objects:
library(zoo)
nums <- c(1402, 1401, 1312)
ym <- as.yearmon(as.character(nums), "%y%m")
giving:
> ym
[1] "Feb 2014" "Jan 2014" "Dec 2013"
回答2:
You need to include day number, otherwise it is impossible to understand what day of month you have in mind, consider:
> strptime('011402', format = "%d%y%m")
[1] "2014-02-01"
回答3:
as.Date requires a full date, with day specified. Since you don't include a day it doesn't know what to do.
You could add any day and it should work like this
date <- 140201
date <- as.Date(as.character(date), format="%y%m%d")
You could use the lubridate package to work with date a little bit easier.
> library(lubridate)
> month(ymd(as.character(140201), label=TRUE)
[1] February
来源：https://stackoverflow.com/questions/37552688/converting-character-into-a-date-format