title: Converting pandas series timestamp to list of unique dates
body: <p>I have a column in pandas dataframe in timestamp format and want to extract unique dates (no time) into a list. I tried following ways doesn't really work, </p>
  
  <pre><code>1. dates =  datetime.datetime(df['EventTime'].tolist()).date()
  2. dates =  pd.to_datetime(df['EventTime']).date().tolist()
  3. dates =  pd.to_datetime(df['EventTime']).tolist().date()
  </code></pre>
  
  <p>can anyone help?</p>