Better error messages
I'm trying to build a dataframe from a list of list and I get an "AssertionError" and I have no idea what I did wrong or what I should do differently. A shorted version of the data and code:

pprint(_fields)
[ 'name',
  'timescited',
  'weight',
  'closeness',
  'betweenness',
  'degree',
  'numberofworks',
  'pagerank',
  'pages',
  'constraint',
  'citationaverage',
  'eigenvector']

pprint(_data2)
[ ['Huselid, Ma', 'Gulati, R', 'Damanpour, F', 'Mcallister, Dj', 'Tsai, Wp'],
  [2721, 5251, 1269, 1287, 2834],
  [6, 17, 6, 3, 6],
  [ 0.0002510562854116362,
    0.00025108339541739277,
    0.00025105435150127433,
    0.00025106898828104144,
    0.0002510723039607744],
  [ 23311.0,
    173596.65383408728,
    79279.82282582425,
    18701.108026093425,
    57261.74716265692],
  [4, 11, 9, 3, 7],
  [6, 17, 6, 3, 6],
  [ 0.0001438440250079284,
    0.0003063098736173118,
    0.00027071793856870986,
    7.839463995668608e-05,
    0.00020047003509480145],
  [130, 387, 148, 68, 88],
  [ 0.28573421556122447,
    0.12411566040831735,
    0.19959178902739988,
    0.3703749360800643,
    0.200788126303937],
  [453, 308, 211, 429, 472],
  [ 5.889013732612275e-08,
    0.0005066654664776551,
    4.567816673280219e-07,
    2.4226314239685797e-06,
    4.069482619394397e-07]]

df = DataFrame(_data2, columns=_fields )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\portabel\Python27\lib\site-packages\pandas\core\frame.py", line 208, in __init__
    copy=copy)
  File "C:\portabel\Python27\lib\site-packages\pandas\core\frame.py", line 273, in _init_ndarray
    block = make_block(values.T, columns, columns)
  File "C:\portabel\Python27\lib\site-packages\pandas\core\internals.py", line 211, in make_block
    do_integrity_check=do_integrity_check)
  File "C:\portabel\Python27\lib\site-packages\pandas\core\internals.py", line 26, in __init__
    assert(len(items) == len(values))
AssertionError


It would be nice if pandas could output a more descriptive error message in case some inputs are not what pandas expects.

Thanks a lot for the lib!

Jan
