parsing two-dimensional array to string in python

Question

please help me in parsing two-dimensional array. For example i have array :

arr = [['a1', 'a2', 'a3'],['b1', 'b2', 'b3']]

and have loop, in them was creating the string with new one array and this one two-demensional array.

ex :

date = ['1 -', '2 -', '3 -']
string = ""
for i in range(len(date)):
   string = string + str(date[i]) + ...

how in this loop i can take string value like :

1 - a1,b1; 2 - a2,b2; 3 - a3,b3;

Thanks for the help

Answer 1

You can do something like thos:

>>> ' '.join('{} {};'.format(a, ','.join(b)) for a, b in zip(date, zip(*arr)))
'1 - a1,b1; 2 - a2,b2; 3 - a3,b3;'

Here first we transpose arr using zip with * :

>>> x = zip(*arr)
>>> x
[('a1', 'b1'), ('a2', 'b2'), ('a3', 'b3')]

Now we can zip this with date to get:

>>> y = zip(date, x)
>>> y
[('1 -', ('a1', 'b1')), ('2 -', ('a2', 'b2')), ('3 -', ('a3', 'b3'))]

Now we can simply loop through this array and perform string formatting and str.join operation on the items to get:

>>> z = ['{} {};'.format(a, ','.join(b)) for a, b in y]
>>> z
['1 - a1,b1;', '2 - a2,b2;', '3 - a3,b3;']

Now all we need to do is join these items using a ' ' :

>>> ' '.join(z)
'1 - a1,b1; 2 - a2,b2; 3 - a3,b3;'