# [SciPy-User] memory error - numpy mean - netcdf4

questions anon questions.anon@gmail....
Tue Aug 23 18:00:36 CDT 2011

```Hi All,
I am receiving a memory error when I try to calculate the Numpy mean across
many NetCDF files.
Is there a way to fix this? The code I am using is below.
Any feedback will be greatly appreciated.

from netCDF4 import Dataset
import matplotlib.pyplot as plt
import numpy as N
from mpl_toolkits.basemap import Basemap
from netcdftime import utime
from datetime import datetime
import os

MainFolder=r"E:/GriddedData/T_SFC/"

all_TSFC=[]
for (path, dirs, files) in os.walk(MainFolder):
for dir in dirs:
print dir
path=path+'/'
for ncfile in files:
if ncfile[-3:]=='.nc':
#print "dealing with ncfiles:", ncfile
ncfile=os.path.join(path,ncfile)
ncfile=Dataset(ncfile, 'r+', 'NETCDF4')
TSFC=ncfile.variables['T_SFC'][4::24,:,:]
LAT=ncfile.variables['latitude'][:]
LON=ncfile.variables['longitude'][:]
TIME=ncfile.variables['time'][:]
fillvalue=ncfile.variables['T_SFC']._FillValue
ncfile.close()

#combine all TSFC to make one array for analyses
all_TSFC.append(TSFC)

big_array=N.ma.concatenate(all_TSFC)
#calculate the mean of the combined array
Mean=big_array.mean(axis=0)
print "the mean is", Mean

#plot output summary stats
map = Basemap(projection='merc',llcrnrlat=-40,urcrnrlat=-33,
llcrnrlon=139.0,urcrnrlon=151.0,lat_ts=0,resolution='i')
map.drawcoastlines()
map.drawstates()
x,y=map(*N.meshgrid(LON,LAT))
plt.title('TSFC Mean at 3pm')
ticks=[-5,0,5,10,15,20,25,30,35,40,45,50]
CS = map.contourf(x,y,Mean, cmap=plt.cm.jet)
l,b,w,h =0.1,0.1,0.8,0.8
cax = plt.axes([l+w+0.025, b, 0.025, h])
plt.colorbar(CS,cax=cax, drawedges=True)

plt.savefig((os.path.join(MainFolder, 'Mean.png')))
plt.show()
plt.close()

print "end processing"
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```