我有一个"日期"向量,其中包含以mm/dd/yyyy格式表示的日期:
head(Entered_Date,5)
[1] 1/5/1998 1/5/1998 1/5/1998 1/5/1998 1/5/1998
我试图根据日期绘制频率变量,但我想按月或年分组日期.就像现在一样,每天有一个频率,但我想按月或年绘制频率.因此,对于1/5/1998,1为1/7/1998和3为1/8/1998,频率为1,我想将其显示为1为1/1998.这是一个相对较大的数据集,从1998年到现在的日期,我想找到一些自动化的方法来实现这一目标.
> dput(head(Entered_Date))
structure(c(260L, 260L, 260L, 260L, 260L, 260L), .Label = c("1/1/1998",
"1/1/1999", "1/1/2001", "1/1/2002", "1/10/2000", "1/10/2001",
"1/10/2002", "1/10/2003", "1/10/2005", "1/10/2006", "1/10/2007",
"1/10/2008", "1/10/2011", "1/10/2012", "1/10/2013", "1/11/1999",
"1/11/2000", "1/11/2001", "1/11/2002", "1/11/2005", "1/11/2006",
"1/11/2008", "1/11/2010", "1/11/2011", "1/11/2012", "1/11/2013",
"1/12/1998", "1/12/1999", "1/12/2001", "1/12/2004", "1/12/2005", ...