pydata/pandas — Issue #813: Implement ordered merge function
Author: wesm
Created: 2012-02-22 22:43:28+00:00
State: open
Labels: Enhancement, prio-high

Something like this:

```
In [87]: df
Out[87]:
Date Px
0 1/1/2001 21.2
1 1/2/2001 22.0
2 1/3/2001 25.0

In [88]: df2
Out[88]:
Individual Date Exercises
0 1 1/1/2001 10
1 2 1/3/2001 5

In [89]: f = lambda x: merge(x, df, how='outer')

In [90]: concat([f(y) for x, y in df2.groupby('Individual')], ignore_index=False)
Out[90]:
Individual Date Exercises Px
0 1 1/1/2001 10 21.2
1 NaN 1/2/2001 NaN 22.0
2 NaN 1/3/2001 NaN 25.0
0 NaN 1/1/2001 NaN 21.2
1 NaN 1/2/2001 NaN 22.0
2 2 1/3/2001 5 25.0
```

but should be able to propagate certain fields and allow others to be NA