title: Trouble converting matrix stored as string in excel to numpy array when using pandas dataframe
body: <p>I am having a hard time reading in an excel file with <code>pandas DataFrame</code> and converting a stored matrix to a <code>numpy array</code>. I think part of the issue is that the matrix is improperly stored. I have no control over the spreadsheet however, this is how it was sent to me.</p>
  
  <p>For instance this is the string stored in a cell</p>
  
  <pre><code>[[[ 0.        0.        0.107851]
    [ 0.        0.       -0.862809]]]
  </code></pre>
  
  <p>I read in the row with <code>DataFrame</code>, and save each cell to a variable. I then try to convert this particular variable to a <code>np.array</code> since those number represent two sets of x, y, z coordinates.</p>
  
  <p>I have tried <code>np.fromstring</code> and <code>np.asarray</code> to no avail. It will convert the string to a numpy array but it will be a terrible mess with the brackets still inside as characters. I have tried using np.squeeze to get rid of the brackets but it says dimension is not 1.</p>
  
  <p>if I use <code>np.asarray(item._coord, dtype=float)</code> then it fails saying it cannot convert the string to float. </p>
  
  <p><code>ValueError: could not convert string to float: '[[[ 0.        0.        0.107851]   [ 0.        0.       -0.862809]]]'</code></p>
  
  <p>There is a '\n' that shows up in the middle of it, between the two lists. I use <code>df = df.replace(r'\n', ' ',regex=True)' to clean out the</code>\n`'s prior to data conversion attempts.</p>
  
  <p>I am stuck</p>