title: Pandas dataframe don't merge on specific column
body: <p>Good evening,</p>
  <p>I have a problem with my df</p>
  <p>Here is df1</p>
  <p><a href="https://i.stack.imgur.com/J1eLK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J1eLK.png" alt="![enter image description here" /></a></p>
  <p>and df2</p>
  <pre><code>    Trimestre   level_0
  0   &quot;A1101&quot; Agriculteurs, éleveurs, sylviculteurs, bûcherons&quot;
  1   &quot;A1401&quot; Maraîchers, jardiniers, viticulteurs&quot;
  2   &quot;A1405&quot; Maraîchers, jardiniers, viticulteurs&quot;
  3   &quot;A1406&quot; Marins, pêcheurs, aquaculteurs&quot;
  4   &quot;N3101&quot; Marins, pêcheurs, aquaculteurs&quot;
  ... ... ...
  123 &quot;K1205&quot; Professionnels de l'action sociale et de l'ori...
  124 &quot;K2104&quot; Professionnels de l'action culturelle, sportiv...
  125 &quot;K2108&quot; Enseignants&quot;
  126 &quot;K2110&quot; Formateurs&quot;
  127 &quot;K2111&quot; Formateurs&quot;
  </code></pre>
  <p>I try to merge df1 with df2 on &quot;Trimestre&quot; column</p>
  <pre><code>df2.Trimestre = df2.Trimestre.astype(str)
  df1.Trimestre = df1.Trimestre.astype(str)
  
  df=pd.merge(df1,df2,on=&quot;Trimestre&quot;)
  </code></pre>
  <p>and nothing appear</p>
  <pre><code>Trimestre   level_0 2010    2011    2012    2013    2014    2015    2016    2017    2018    2019    2020
  </code></pre>
  <p>Help me pls</p>
  <p>EDIT: Here is the output of df.head().to_dict() to reproduce the error</p>
  <p>df1</p>
  <pre><code>{'Trimestre': {0: 'A1101 ',
    1: 'A1201 ',
    2: 'A1202 ',
    3: 'A1203 ',
    4: 'A1204 '},
   '2010': {0: 2630, 1: 1380, 2: 4450, 3: 20330, 4: 130},
   '2011': {0: 2790, 1: 1500, 2: 3670, 3: 20040, 4: 90},
   '2012': {0: 2700, 1: 1320, 2: 4020, 3: 19140, 4: 130},
   '2013': {0: 2970, 1: 1690, 2: 3520, 3: 20500, 4: 140},
   '2014': {0: 2680, 1: 1980, 2: 2790, 3: 16900, 4: 150},
   '2015': {0: 2440, 1: 1780, 2: 2640, 3: 16310, 4: 170},
   '2016': {0: 3600, 1: 1980, 2: 2540, 3: 17680, 4: 90},
   '2017': {0: 2930, 1: 2470, 2: 2510, 3: 18520, 4: 130},
   '2018': {0: 2740, 1: 2010, 2: 2130, 3: 19280, 4: 150},
   '2019': {0: 1600.0, 1: 1760.0, 2: 1050.0, 3: 14260.0, 4: 80.0},
   '2020': {0: 11140, 1: 6490, 2: 14000, 3: 76580, 4: 510}}
  </code></pre>
  <p>df2</p>
  <pre><code>{'Trimestre': {0: 'A1101', 1: 'A1401', 2: 'A1405', 3: 'A1406', 4: 'N3101'},
   'level_0': {0: 'Agriculteurs, éleveurs, sylviculteurs, bûcherons&quot;',
    1: 'Maraîchers, jardiniers, viticulteurs&quot;',
    2: 'Maraîchers, jardiniers, viticulteurs&quot;',
    3: 'Marins, pêcheurs, aquaculteurs&quot;',
    4: 'Marins, pêcheurs, aquaculteurs&quot;'}}
  </code></pre>