title: Pandas Data Frame to_csv with more separator
body: <p>I have a file of 40 columns and 600 000 rows. After processing it in pandas dataframe, i would like to save the data frame to csv with different spacing length. There is a sep kwarg in df.to_csv, i tried with regex, but i'm getting error</p>
  
  <blockquote>
    <p>TypeError: "delimiter" must be an 1-character string.</p>
  </blockquote>
  
  <p>I want the output with different column spacing, as shown below</p>
  
  <pre><code>A    B  C   D    E F  G
  1    3  5   8    8 9  8
  1    3  5   8    8 9  8
  1    3  5   8    8 9  8
  1    3  5   8    8 9  8
  1    3  5   8    8 9  8
  </code></pre>
  
  <p>Using the below code i'm getting the tab delimited. which are all with same spacing.     </p>
  
  <pre><code>df.to_csv("D:\\test.txt", sep = "\t", encoding='utf-8')
  
  A  B  C  D  E  F  G
  1  3  5  8  8  9  8
  1  3  5  8  8  9  8
  1  3  5  8  8  9  8
  1  3  5  8  8  9  8
  1  3  5  8  8  9  8
  </code></pre>
  
  <p>I don't want to do looping, It might take lot of time for 600k lines.</p>