title: can't add a string element to numpy zeros array
body: <p>I'm new to python and numpy and I wanted to create an array with mixed data types but I get this error : </p>
  
  <pre><code>&gt;&gt;&gt; m = np.zeros((5,10))
  &gt;&gt;&gt; m[0,0] = 'e'
  
  Traceback (most recent call last):
  File "&lt;pyshell#17&gt;", line 1, in &lt;module&gt;
  m[0,0] = 'e'
  ValueError: could not convert string to float: e
  </code></pre>
  
  <p>I'm using numpy beacuse it's easier to implement bigger sized arrays and edit them. 
  I tried to change the data type of the array but I couldn't find any suitable one.</p>