Pandas merge tables: only distinct Ids from second table
<p>I am trying to figure out if it's possible to join/merge/concat two tables and just instead of 'outer' I'd like to pick the distinct Ids from the second table with the pandas built-in options. </p>

<p>Right now I am doing something along the lines and 
I have the feeling that my code is not very elegant:</p>

<pre><code>a = [['a', '1.2', '4.2'], ['b', '70', '0.03'], ['c', '8', '1']]
b = [['a', '52', '49'], ['b', '23', '0.05'], ['x', '5', '0']]
df1 = pd.DataFrame(a, columns=['id_col', 'two', 'three'])
df2 = pd.DataFrame(b, columns=['id_col', 'two', 'three'])


# remove df2 entries also in df1
different_ids = set(df2.id_col).difference(set(df1.id_col))
df2 = df2[df2.id_col.isin(different_ids)]
# merge data frames
df_merged = pd.concat([df1,df2])
</code></pre>

<p>the merged df should have the entries a,b,c from df1 and x from df2.</p>