Pandas: plot the graph of unique values
<p>I have a column in pandas dataframe: </p>

<pre><code>df.['A']:
1
1
1
2
2
3
1
2
3
1
2
3
</code></pre>

<p>I need to plot a histogram which will show how much if 1, of 2 and of 3 i have.
For that i firstly count the amount of all 1, 2, and 3:</p>

<pre><code>print df.groupby(df.index)['A'].nunique()
</code></pre>

<p>but instead of getting</p>

<pre><code>1   5
2   4
3   3
</code></pre>

<p>i get</p>

<pre><code>1
1
1
</code></pre>

<p>what is my mistake? and may be there is a better way of plotting it withpout previous extraction of counted data?</p>