Zip Function:
When there are 2 lists and we need to iterator over both the lists parallelly, we can use the zip function.
Lets understand Zip function using the below example.
a = [1,2,3,4]
b = ['a','b','c','d']
for i, j in zip(a,b):
print(str(i)+','+j)
1,a 2,b 3,c 4,d
Here, notice that we have used 2 variables for iteration. i and j.
“i” will be assigned with the items from “a” and “j” will be assigned with the items from “b” respectively.
Exceptions in Zip:
if only one variable is provided instead of i and j, then NameError will be raised.
for obj in zip(a,b):
print(obj)
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-13-4323aa7a8932> in <module>
----> 1 for obj in zip(a,b):
2 print(obj)
NameError: name 'a' is not defined
Another Example:
Lets create a Tuple from 2 lists.
names = ['cat','dog','fox','lion']
index = [1,2,3,4]
with_index = list(zip(names,index))
print(with_index)
[('cat', 1), ('dog', 2), ('fox', 3), ('lion', 4)]
Enumerate Function:
The Enumerate function provides an ability to use the counter value of the iteration.
Using this function, we can use an index of the item as a counter.
a = [20,40,50,60]
b=[6,7,8,9,10]
for index,a in enumerate(a):
print("Index of",a,"is",index)
Index of 20 is 0 Index of 40 is 1 Index of 50 is 2 Index of 60 is 3
Bonus Tip – Using both zip and enumerate together:
a = [20,40,50,60]
b=[6,7,8,9,10]
for index,(a,b) in enumerate(zip(a,b)):
print(index, (a*b))
0 120 1 280 2 400 3 540