title: Why is python pandas dataframe rounding my values?
body: <p>I do not understand why pandas dataframe is rounding the values in my column where I divide the values of two other columns. I want the numbers in the new colums with two decimals, but the values are rounded. I have checked the dtypes of the columns and both are "float64". </p>
  
  <pre><code>import pandas as pd
  import numpy as np
  
  
  # CURRENT DIRECTORY 
  cd = os.path.dirname(os.getcwd())
  
  # concatenate csv files
  dfList = []
  
  for root, dirs, files in os.walk(cd):
      for fname in files:
          if re.match("output_contigs_SCMgenes.csv", fname):
              frame = pd.read_csv(os.path.join(root, fname))
              dfList.append(frame)    
  
  df = pd.concat(dfList)
  
  #replace nan in SCM column with 0
  df['SCM'].fillna(0, inplace=True)
  
  #add column with genes/SCM
  df['genes/SCM'] = df['genes']/df['SCM']
  </code></pre>
  
  <p>The output is as follows:</p>
  
  <pre><code>    genome  contig  genes  SCM  genes/SCM
  0    20900      48      1    0        inf
  1    20900      37    130  103          1
  2    20900      35      1    1          1
  3    20900       1     79   66          1
  4    20900      66      5    3          2
  </code></pre>
  
  <p>But I want that my last column does not contain rounded values, but values with at least 2 decimals. </p>