I have a relatively simple problem. Two pandas dataframes:

```
    a b
one 1 2

```

and 

```
    a c
one 1 3

```

And I want to get

```
    a b c
one 1 2 3

```

I have tried pd.join and pd.concat, which give me duplicate rows or columns, and pd.merge, which merges the data but loses index name.

```
<!-- language: Python -->
a=pd.DataFrame({'a':{'one':1},'c':{'one':3}})
b=pd.DataFrame({'a':{'one':1},'b':{'one':2}})
pd.merge(a,b)

pd.merge(a,b)

   a  c  b
0  1  3  2

```

I acknowledge that I may have missed something trivial about pandas or trying to solve problem in a wrong way.