Saving arrays as columns with np.savetxt

Question

I am trying to do something that is probable very simple. I would like to save three arrays to a file as columns using \'np.savetxt\' When I try this

x = [1,2,3         


        

Answer 1

Use numpy.c_[]:

np.savetxt('myfile.txt', np.c_[x,y,z])

Answer 2

Use zip:

np.savetxt('myfile2.txt', zip(x,y,z), fmt='%.18g')

For python3 list+zip:

np.savetxt('myfile.txt', list(zip(x,y,z)), fmt='%.18g')

To understand the workaround see here: How can I get the "old" zip() in Python3? and https://github.com/numpy/numpy/issues/5951.

Answer 3

Use numpy.transpose():

np.savetxt('myfile.txt', np.transpose([x,y,z]))

I find this more intuitive than using np.c_[].

Answer 4

I find numpy.column_stack() most intuitive:

np.savetxt('myfile.txt', np.column_stack([x,y,z]))