title: extracting data from nc files using scipy
body: <p>I am trying to extract values of some parameters from an <code>nc</code> file, but my code doesn't work for the <code>slp</code> parameter, though it works for the other parameters.  The code is showing me negative values for <code>slp</code> which means the importing of the data is not correct.</p>
  
  <p>I used this script:</p>
  
  <pre><code>import numpy as np
  import matplotlib as mpl
  mpl.use('agg')
  from mpl_toolkits.basemap import Basemap
  from scipy.io import netcdf_file as nc
  from pylab import *
  
  from datetime import datetime
  from datetime import timedelta
  from glob import glob
  
  
  files1 = glob('n1*nc')
  files1.sort()
  MVAL1 = -32767
  for item in files1:
    clf()
    f1 = nc(item)
    times=f1.variables['time'] 
    lon = f1.variables['longitude'].data
    lat = f1.variables['latitude'].data
    slp = f1.variables['msl'].data   
    # to convert to hpa
    slp = slp*0.01
    dims = slp.shape                   
    print slp.shape, np.max(slp), np.min(slp)
  </code></pre>
  
  <p>The results are</p>
  
  <pre><code>(73, 121) 327.67 -327.66
  </code></pre>
  
  <p>while when I check it in <code>Panoply</code> the min and max values are different.</p>
  
  <p>How do I solve this problem?</p>