python - How can I get the mean value of an array? -

i trying calculate mean value of last 10 elements. first reading out data file:

np.genfromtxt(filename,skip_header=6, names=true) 

first tried use numpy.mean function getting following error:

typeerror: cannot perform reduce flexible type 

so decided of writing function:

def get_mean_values( marray, nr ):     """     """     # creating empty array     tmp = np.delete( marray[-1:], 0, 0 )      key in marray.dtype.fields:         tmp[key] = np.append( tmp[key], np.mean( marray[key][nr:] ) )       print tmp     return tmp 

but tmp array empty. how can calculate , store mean value of last 10 elements.

this how data looks

array([ (99.9, 9.0),        (100.0, 9.0) ....],        dtype=[('time', '<f8'), ('horwind', '<f8')]) 

the mean function works fine long specific enough :)

import numpy  x = numpy.array([(99.9, 9.0),        (100.0, 9.0)],        dtype=[('time', '<f8'), ('horwind', '<f8')])  print 'time', x['time'].mean() print 'horwind', x['horwind'].mean() 

output:

time 99.95 horwind 9.0