如何从两个列表创建元组，以便重复一个列表元素

Question

I'm trying to join 2 list such that the values in the first list get joined to the values in the second list in order and then join again when the list one items have exhausted...

worker_tables=['table1','table2']

mylist = [['val1','val2'], ['val3','val4'],['val5','val6'],['val7','val8'],['val9','val10']]

mylist_tup = zip(mylist, worker_tables)

the result i'm getting is--

print mylist_tup

[(['val1', 'val2'], 'table1'), (['val3', 'val4'], 'table2')] 

as you see, it's not joining back to table1 and table2 fields from the first list..

desired output=

 [(['val1', 'val2'], 'table1'),(['val3', 'val4'], 'table2'), (['val5', 'val6'], 'table1'),(['val7', 'val8'], 'table2'), (['val9', 'val10'], 'table1')]

Answer 1

You can use itertools.cycle to achieve the desired result:

from itertools import cycle

mylist_tup = zip(mylist, cycle(worker_tables))

This will cycle through the values of worker_tables as many times as needed.

Answer 2

You can repeat the worker_table list items out to the length of mylist:

worker_tables=['table1','table2']

mylist = [['val1','val2'], ['val3','val4'],['val5','val6'],['val7','val8'],['val9','val10']]

mylist_tup = zip(mylist, worker_tables * int(len(mylist) / len(worker_tables)))