title: pandas dataframe match column from external file
body: <p>I have a df with </p>
  
  <pre><code>col0 col1 col2 col3
  a    1    2    text1
  b    1    2    text2
  c    1    3    text3
  </code></pre>
  
  <p>and i another text file with</p>
  
  <pre><code>col0 col1 col2
  met1 a    text1
  met2 b    text2
  met3 c    text3
  </code></pre>
  
  <p>how do i match row values from col3 in my first df to the text file col2 and add to previous df only col0 string with out changing the structure of the df </p>
  
  <p>desired output:</p>
  
  <pre><code>col0 col1 col2 col3  col4
  a    1    2    text1 met1
  b    1    2    text2 met2
  c    1    3    text3 met3
  </code></pre>