This program creates a CArray using PyTables. A numpy array is initialized and used to fill a hyperslab of a CArray. Slices of the array are then printed.

CArrayHDF.py

import sys
import numpy as np
import tables as tb

filename='carrayEx1.h5'

fileh=tb.openFile(filename, 'w')
carray = fileh.createCArray(fileh.root, 'carray', tb.UInt32Atom(), shape=(200,300))

a=np.array(np.arange(5*3)).reshape((5,3))
carray[10:15,10:15:2] =a

print ""
print "The array, ", a[:,:]
print ""
print "is written into a hyperslab in CArray."
print ""
print "The portion of the CArray,"
print "carray[10:15,10:15:2] = " 
print ""
print carray[10:15,10:15]

print ""
print "type of a:", type(a)
print "dtype of a: ",a.dtype
print "type of carray:", type(carray)
#print "type of carray:", carray.dtype

print""
print "Converting the pytables array into a numpy array:"

#Method for fast conversion from a pytables array to a numpy array
def fast_conversion(hdfarray):
	a=np.empty(shape=hdfarray.shape,dtype=hdfarray.dtype)
	a[:]=hdfarray[:]
	return a

#Conversion from a pytables array to a numpy array
b = fast_conversion(carray)

print "type of b:", type(b)
print "dtype of b:", b.dtype
print ""

carray[1,1]=10**9 
#print "picking a very high value for carray[1,1]: ", carray[1,1]
#print ""

fileh.close()

#Reopen and read another hyperslab from the hdf file

h5f=tb.openFile(filename)
print h5f
print ""
print h5f.root.carray[5:15,5:15]

h5f.close()

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