title: Modify element [0][0] in a Python 2D list
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/14190513/append-to-a-sublist-appends-to-every-sublist">append to a sublist appends to every sublist</a>  </p>
  </blockquote>
  
  
  
  <p>The 2D list is initialized as <code>grid=[[False]*N] *N</code></p>
  
  <p>print grid produces:</p>
  
  <pre><code>[[False, False, False, False], [False, False, False, False], [False, False, False, False], [False, False, False, False]]
  </code></pre>
  
  <p>Now I want the element in row 1 and column 1 to be true. I only want the element in row 1 and column 1 to be true. Other elements must be false.</p>
  
  <p><code>grid[0][0]=True</code></p>
  
  <p>After I set grid[0][0] to true, print grid produces:</p>
  
  <p><code>[[True, False, False, False], [True, False, False, False], [True, False, False, False], [True, False, False, False]]</code></p>
  
  <p>But the first element of every row is now True, but I only want the first element of the first row to be true.</p>
  
  <p>Please help. I'm new to Python.</p>