title: What is the fastest way of searching for string in 2d array
body: <p>I need to search for a string within the first column of a 2d array. The most obvious way is</p>
  
  <pre><code>for i in range (0, len(list)):
  if list[i][0]==searchstring:
     list[i][4]=do_a_bunch_of_stuff
  </code></pre>
  
  <p>I need to know where "i" is so that i can do_a_bunch_of_stuff to the same row.
  I need to loop through all of the rows in the 2d array</p>
  
  <p>Speed is the main factor not pretty code. What is the fastest (CPU performance) way of doing this?</p>