title: How to change a .csv file to .dat file using pandas?
body: <p>For example, the csv file looks like this: <a href="https://i.stack.imgur.com/RRovd.png" rel="nofollow noreferrer">csv content</a>. How to change it to .dat file like this using '|':</p>
  <p>a 1|b 2|c 3|d 4|...<br />
  a 2|b 3|c 4|d 5|...<br />
  a 3|b 4|c 5|d 6|...<br />
  ...</p>