我有两个大数据集,df1和df2.第一个数据集df1包含列'ID'和'actual.data'.
df1 <- data.frame(ID=c(1,1,1,2,3,4,4), actual.date=c('10/01/1997','2/01/1998','5/01/2002','7/01/1999','9/01/2005','5/01/2006','2/03/2003'));
dcis <- grep('date$',names(df1));
df1[dcis] <- lapply(df1[dcis],as.Date,'%m/%d/%Y');
df1;
ID actual.date
1 1 1997-10-01
2 1 1998-02-01
3 1 2002-05-01
4 2 1999-07-01
5 3 2005-09-01
6 4 2006-05-01
7 4 2003-02-03
第二个数据集df2包含两个日期字段,'before,date'和'after.date',分别代表开始日期和结束日期:
df2 <- data.frame(ID=c(1,1,1,2,3,4,4,4), before.date=c('10/1/1996','1/1/1998','1/1/2000','1/1/2001','1/1/2001','1/1/2001','10/1/2004','10/3/2004'), after.date=c('12/1/1996','9/30/2003','12/31/2004','3/31/2006','9/30/2006','9/30/2005','12/30/2004','11/28/2004') );
dcis <- grep('date$',names(df2));
df2[dcis] <- lapply(df2[dcis],as.Date,'%m/%d/%Y');
df2;
ID before.date after.date
1 1 1996-10-01 1996-12-01
2 1 1998-01-01 2003-09-30
3 1 2000-01-01 2004-12-31
4 2 2001-01-01 2006-03-31
5 3 2001-01-01 2006-09-30
6 4 2001-01-01 2005-09-30
7 4 2004-10-01 2004-12-30 …