title: Error in reading HDF5 using h5py
body: <p>I have saved my dataset in this form as mentioned in the following image (HDF5 format). So I have different groups i.e. 4, 2, 40 etc. and for each group I have 2 datasets <code>Annotation</code> and <code>Features</code>. I have save them successfully using code but I am unable to load them back.</p>
  
  <p>Strange thing is the error occurs only when I try to read <code>Annotation</code>. And reading works fine when I try to read <code>Features</code>.  </p>
  
  <p>I am using the following code:</p>
  
  <pre><code>dataSet = np.array([])
  annotation = np.array([])
  hdf5Object = readHDF5File('abc.hdf5','r')
  w = 2
  myGroup = hdf5Object[str(w)]
  
  dataSet = np.array(myGroup['Features'])
  annotation = np.array(myGroup['Annotation'])
  </code></pre>
  
  <p>Please enlighten me here as I am struggling a lot for this for a while now. Thanks.</p>
  
  <p><a href="https://i.stack.imgur.com/TbWrJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TbWrJ.png" alt="View of HDF5 generated using ViTables 2.1"></a></p>
  
  <p><strong>EDIT 1</strong></p>
  
  <p>I am getting the following error when I read <code>Annotation</code></p>
  
  <pre><code>Traceback (most recent call last):
    File "xyz.py", line 76, in getAllData
      annotation = np.array(myGroup['Annotation'])
    File "/usr/lib/python2.7/dist-packages/h5py/_hl/group.py", line 153, in __getitem__
      oid = h5o.open(self.id, self._e(name), lapl=self._lapl)
    File "h5o.pyx", line 173, in h5py.h5o.open (h5py/h5o.c:3403)
  KeyError: "unable to open object (Symbol table: Can't open object)"
  </code></pre>
  
  <p><strong>EDIT 2</strong></p>
  
  <p>So the hdf5 file was formed in 2 steps, in 1st step <code>Features</code> were calculated as follows:</p>
  
  <pre><code>features = &lt;numpy array of thousand rows and 100 columns contains only floating numbers&gt;
  w = 2
  f = h5py.File('abc.hdf5', 'a')
  myGroup = f[str(w)]
  myGroup.create_dataset('Features', data=features)
  </code></pre>
  
  <p>For different <code>w</code> file was appended and features were calculated at different times.</p>
  
  <p>For annotation, same kind of procedure is used. <code>Annotation</code> contains only floating points as well. </p>
  
  <p><strong>EDIT 3</strong></p>
  
  <p>In the following image is content of data in <code>Annotation</code> and <code>Features</code> of one <code>w</code>. Left window is <code>Annotation</code> and right one is <code>Features</code>.</p>
  
  <p><a href="https://i.stack.imgur.com/pN2JE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pN2JE.png" alt="enter image description here"></a> </p>