title: Remove variables from a recarray by variable name
body: <p>I need to concatenate 2 rec.arrays (same procedure I do for all other in my work). Problem I have is one of the documents I read for the array, has 2 extra variables that I need to remove to match the variables of the other array to concatenate. I have tried several things, like using the index to remove, all lead to error.</p>
  <p>This is the array</p>
  <pre><code>vswhr1
  rec.array([('ny20110325s0a06c.001', 2011.23149798,  84.49677, 11.9223, 1.000e+00, 78.923, 11.923, 0.024, 0.024, 77.286, 189.465  ,  1.688, 180.     , 0.0019, 0., 0.00167, 60., 1003.84003, -15.7, 1003.84003, 65.8, -1., 0.    , -1., -1., 9.8765e+35, 9.8765e+35, 5.96541e+21, 2.60898e+19, 8.45080e+21, 7.92632e+19, 8.74633e+21, 8.68890e+19),
             ('ny20110325s0a06c.002', 2011.23150704,  84.50007, 12.0017, 2.000e+00, 78.923, 11.923, 0.024, 0.024, 77.325, 190.686  ,  1.694, 180.     , 0.0019, 0., 0.00167, 60., 1003.83002, -16. , 1003.83002, 68.7, -1., 0.    , -1., -1., 9.8765e+35, 9.8765e+35, 5.93553e+21, 2.54199e+19, 8.43518e+21, 7.75936e+19, 8.72990e+21, 8.60191e+19),
             ('ny20110325s0a06c.003', 2011.23150736,  84.50019, 12.0045, 3.000e+00, 78.923, 11.923, 0.024, 0.024, 77.326, 190.728  ,  1.694, 180.     , 0.0019, 0., 0.00167, 60., 1003.83002, -16.1, 1003.83002, 68.9, -1., 0.    , -1., -1., 9.8765e+35, 9.8765e+35, 5.93643e+21, 2.59443e+19, 8.42675e+21, 8.17653e+19, 8.73537e+21, 8.68880e+19),
             ...,
             ('ny20180919s0i06c.0042', 2018.71887239, 262.38843,  9.3221, 1.234e+03, 78.923, 11.923, 0.024, 0.027, 78.69 , 152.737  , -1.722, 180.00999, 0.0019, 0., 0.00188, 60., 1011.84003,  -2.2, 1011.84003, 77.6, -1., 0.0125, -1., -1., 9.8765e+35, 9.8765e+35, 2.11077e+22, 8.61874e+19, 8.72151e+21, 5.33405e+19, 9.01945e+21, 7.07619e+19),
             ('ny20180920s0i06c.0491', 2018.72160282, 263.38504,  9.2407, 1.235e+03, 78.923, 11.923, 0.024, 0.034, 79.177, 151.62399, -1.735, 180.00999, 0.0019, 0., 0.00188, 60., 1006.65997,   0. , 1006.65997, 62.8, -1., 0.0095, -1., -1., 9.8765e+35, 9.8765e+35, 1.96888e+22, 7.48627e+19, 8.70719e+21, 5.40175e+19, 8.97596e+21, 7.49834e+19),
             ('ny20180920s0i06c.0492', 2018.72161188, 263.38834,  9.3201, 1.236e+03, 78.923, 11.923, 0.024, 0.034, 79.072, 152.83299, -1.729, 180.00999, 0.0019, 0., 0.00188, 60., 1006.65997,  -0.6, 1006.65997, 64.6, -1., 0.0078, -1., -1., 9.8765e+35, 9.8765e+35, 1.94867e+22, 7.83111e+19, 8.71765e+21, 4.97304e+19, 8.97784e+21, 7.23055e+19)],
            dtype=[('spectrum', '&lt;U21'), ('year', '&lt;f8'), ('day', '&lt;f8'), ('hour', '&lt;f8'), ('run', '&lt;f8'), ('lat', '&lt;f8'), ('long', '&lt;f8'), ('zobs', '&lt;f8'), ('zmin', '&lt;f8'), ('solzen', '&lt;f8'), ('azim', '&lt;f8'), ('osds', '&lt;f8'), ('opd', '&lt;f8'), ('fovi', '&lt;f8'), ('amal', '&lt;f8'), ('graw', '&lt;f8'), ('tins', '&lt;f8'), ('pins', '&lt;f8'), ('tout', '&lt;f8'), ('pout', '&lt;f8'), ('hout', '&lt;f8'), ('sia', '&lt;f8'), ('fvsi', '&lt;f8'), ('wspd', '&lt;f8'), ('wdir', '&lt;f8'), ('luft', '&lt;f8'), ('luft_error', '&lt;f8'), ('h2o', '&lt;f8'), ('h2o_error', '&lt;f8'), ('co2', '&lt;f8'), ('co2_error', '&lt;f8'), ('3co2', '&lt;f8'), ('3co2_error', '&lt;f8')])
  
  vswhr1.shape 
  (1236,) 
  </code></pre>
  <p>*irrelevant numbers</p>
  <p>I need to delete the las 2 variables  ('3co2', '&lt;f8'), ('3co2_error', '&lt;f8')</p>
  <p>Thank you</p>