I have dataframe like this,
| Year | A | B |
|---|---|---|
| 2011 | 23 | 98 |
| 2012 | 22 | 87 |
| 2013 | 32 | 34 |
| 2014 | 232 | 34 |
| 2015 | 443 | 33 |
How can I change above dataframe into like this ?
| Year | C |
|---|---|
| 2011-A | 23 |
| 2011-B | 98 |
| 2012-A | 22 |
| 2012-B | 87 |
| 2013-A | 32 |
| 2013-B | 33 |
| 2014-A | 232 |
| 2014-B | 34 |
| 2015-A | 443 |
| 2015-B | 32 |