Enumerate two python lists simultaneously?
PythonListPython Problem Overview
How do I enumerate two lists of equal length simultaneously? I am sure there must be a more pythonic way to do the following:
for index, value1 in enumerate(data1):
print index, value1 + data2[index]
I want to use the index and data1[index] and data2[index] inside the for loop.
Python Solutions
Solution 1 - Python
Use zip for both Python2 and Python3:
for index, (value1, value2) in enumerate(zip(data1, data2)):
print(index, value1 + value2) # for Python 2 use: `print index, value1 + value2` (no braces)
Note that zip runs only up to the shorter of the two lists(not a problem for equal length lists), but, in case of unequal length lists if you want to traverse the whole list then use itertools.izip_longest.
Solution 2 - Python
for i, (x, y) in enumerate(zip(data1, data2)):
In Python 2.x, you might want to use itertools.izip instead of zip, esp. for very long lists.
Solution 3 - Python
from itertools import count
for index, value1, value2 in zip(count(), data1, data2):
print(index, value1, value2)
Source: http://www.saltycrane.com/blog/2008/04/how-to-use-pythons-enumerate-and-zip-to/#c2603
Solution 4 - Python
Althought this is not very clear what you look for,
>>> data1 = [3,4,5,7]
>>> data2 = [4,6,8,9]
>>> for index, value in enumerate(zip(data1, data2)):
print index, value[0]+value[1]
0 7
1 10
2 13
3 16
Solution 5 - Python
Since it has been mentioned that the length are equal,
for l in range(0, len(a)):
print a[l], b[l]
Solution 6 - Python
Suppose you want to use zip:
>>> for x in zip([1,2], [3,4]):
... print x
...
(1, 3)
(2, 4)