[Numpy-discussion] Help making better use of numpy array functions
mdekauwe
mdekauwe@gmail....
Thu Nov 26 10:33:03 CST 2009
Yep that will do nicely, code becomes
import sys, os, glob
import numpy as np
def averageEightDays(files, numrows, numcols, year, doy):
""" Read in 8 files at a time, sum the valid LST, keep a count of
the valid pixels and average the result every 8days. """
nodatavalue = -999.0
# break the files up into chunks of 8
filenames = glob.glob(os.path.join(path, files))
filenames.sort()
filenamesList = [filenames[n:n+8] for n in xrange(0, len(filenames), 8)]
for fchunk in filenamesList:
# fill with nodata values, in case there are less than 8 days
data8days = np.ones((8, numrows, numcols), dtype=np.float32) * -999.0
avg8days = np.zeros((numrows, numcols), dtype=np.float32)
for day in xrange(len(fchunk)):
fname = fchunk[day]
try:
f = open(fname, 'rb')
except IOError:
print "Cannot open outfile for read", fname
sys.exit(1)
data8days[day] = np.fromfile(f, dtype=np.float32).reshape(numrows,
numcols)
# build an array (ndays, nrow, ncols) of True and False for the pixel
count
# when these are summed we get the relative contributions
weights = data8days > nodatavalue
# np.average doesn't accept a weight of zero, COMMENT ME
weights[0] |= (weights.sum(axis=0) == 0)
pixelCount = weights.sum(axis=0)
avg8days = np.average(data8days, axis=0, weights=weights)
doy += 8
#print year,':',doy
outfile = "lst_8day1030am_" + str(year) + str(doy) + ".gra"
write_outputs(outfile, avg8days)
outfile = "pixelcount_8day1030am_" + str(year) + str(doy) + ".gra"
write_outputs(outfile, pixelCount)
def write_outputs(outfile, data):
opath = "/users/eow/mgdk/research/HOFF_plots/LST/8dayLST"
try:
of = open(os.path.join(opath, outfile), 'wb')
except IOError:
print "Cannot open outfile for write", outfile
sys.exit(1)
# empty stuff
data.tofile(of)
of.close()
if __name__ == "__main__":
numrows = 332
numcols = 667
path = "/users/eow/mgdk/research/HOFF_plots/LST/gridded_03/"
averageEightDays('lst_scr_2006*.gra', numrows, numcols, year=2006, doy=122)
averageEightDays('lst_scr_2007*.gra', numrows, numcols, year=2007, doy=122)
--
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