Python: Writing Large Array Of Arrays To Text File

I'm new to Python and I have a solution for this but it seems slow and silly, so I wondered if there is a better way? Say I have a matrix defined like this: mat = [['hello']*4 for

Solution 1:

If I understand your question correctly, you could do:

f.writelines(' '.join(row) +'\n'forrowin mat)

or

f.write('\n'.join(' '.join(row) forrowin mat))

The first one has the advantage of being a generator expression that only makes a concatenated string copy of the currentline

And if your matrix entries are not strings, you could do:

f.writelines(' '.join(str(elem) for elem inrow) +'\n'forrowin mat)

EDIT

It appears that the file.writelines() method evaluates the entire generator expression before writing it to the file. So the following would minimize your memory consumption:

forrowin mat:
    f.write(' '.join(row) +'\n')

Solution 2:

You could use csv module:

import csv

withopen(outfile, 'wb') as f:
     csv.writer(f, delimiter=' ').writerows(mat)