How do I save a 3D Python/NumPy array as a text file?

Question

I have to launch a great number of calculations, and I have to save a 2D file text each time, so I would like to store results in "real-time" as a 3D text file with each slice corresponding to one calculation result.

The first calculation is OK, but when I do the second calculation, during the "np.loadtxt" step, the array dimensions become 2D... So I can't reach my aim... and I can't do a reshape when I begin to dimensions (... , ... , 1)

#MY FIRST RESULTS
test1 = open("C:/test.txt", "r")
test_r = np.genfromtxt(test, skip_header=1)
test_r = np.expand_dims(test_r, axis=2) #I create a new axis to save in 3D
test1.close()

#I test if the "Store" file to keep all my results is created.
try:
    Store= np.loadtxt('C:/Store.txt')
except:
    test=1

#If "Store" is not created, I do it or I concatenate in my file.
if test ==1:
    Store= test_r
    np.savetxt('C:/Store.txt', Store)
    test=2
else:
    Store = np.concatenate((Store,test_r), axis=2)
    np.savetxt('C:/Store.txt', Store)


#MY SECOND RESULTS
test2 = open("C:/test.txt", "r")
test_r = np.genfromtxt(test, skip_header=1)
test_r = np.expand_dims(test_r, axis=2)
test2.close()

#I launch the procedure again to "save" the results BUT DURING THE LOADTXT STEP THE ARRAY DIMENSIONS CHANGE TO BECOME A 2D ARRAY...
try:
    Store= np.loadtxt('C:/Store.txt')
except:
    test=1


if test ==1:
    Store= test_r
    np.savetxt('C:/Store.txt', Store)
    test=2
else:
    Store = np.concatenate((Store,test_r), axis=2)
    np.savetxt('C:/Store.txt', Store)

Answer 1

Here's an example of cPickle:

import cPickle

# write to cPickle
cPickle.dump( thing_to_save, open( "filename.pkl", "wb" ) )

# read from cPickle
thing_to_save = cPickle.load( open( "filename.pkl", "rb" ) )

The "wb" and "rb" parameters to the open() function are important. CPickle writes objects in a binary format, so using just "w" and "r" won't work.