I have several similarly structured pandas dataframes stored in a dictionary. I access a dataframe in the following way.

```
ex_dict[df1]
date        df1price1   df1price2
10-20-2015     100         150
10-21-2015      90         100

```

I want to merge all of these dataframes into one dataframe by date. The dates are overlapping, but not all dataframes include all dates.

I need to go from this

```
df1
date        df1price1   df1price2
10-20-2015     100         150
10-21-2015      90         100
10-22-2015     100         140

df2
date        df2price1   df2price2
10-20-2015     110         140
10-21-2015      90         110
10-23-2015     110         120

df3
date        df3price1   df3price2
10-20-2015     100         150
10-22-2015      90         100
10-23-2015      80         130

```

to this:

```
df_all
date        df1price1   df1price2 ... df3price1   df3price2
10-20-2015     100         150    ...    100         150
10-21-2015      90         100    ...    NaN         NaN
10-22-2015     100         140    ...     90         100
10-23-2015     NaN         NaN    ...     80         130

```

I've tried lots of things, but I can't get it to work, short of repeatedly merging 2 at a time to create a new dataframe and then remerging onto that. The number of dataframes I need to merge varies between 4 and 10, so I need a way to do this automatically (hence why I thought a passing a dict might work). 

Any help on this would be incredibly appreciated.