比如,下表中标红的(所有变量都缺失的)就删掉,但下标为横线的(不是所有变量都缺失的)不删掉。谢谢!
数据实例如下:
id | year | var1 | var2 |
1 | 2000 | . | . |
1 | 2001 | . | 12 |
1 | 2002 | 6 | 2 |
1 | 2003 | 17 | 12 |
1 | 2004 | 7 | 15 |
1 | 2005 | 17 | 10 |
1 | 2006 | 6 | 17 |
1 | 2007 | . | 4 |
1 | 2008 | . | . |
1 | 2009 | . | . |
2 | 2000 | . | . |
2 | 2001 | 11 | 15 |
2 | 2002 | 8 | 17 |
2 | 2003 | 5 | 19 |
2 | 2004 | 8 | 3 |
2 | 2005 | 4 | 5 |
2 | 2006 | 1 | 3 |
2 | 2007 | 15 | 18 |
2 | 2008 | 1 | . |
2 | 2009 | . | . |