I have following condition:
a=[]
for i in list1:
for j in list2:
if i==j:
a.append(i)
I want to add a statement a.append(np.nan) if i!=j after looping through list2.
i.e
After iterating through inner for loop, if i don't find any i==j then it should append nan.
PS.: I have such lists that there will be at-most once i==j.
How to do it?
Try this:
import numpy as np
list1 = [1,2,3,4]
list2 = [2,1,3,5]
a = [i if i in list2 else np.nan for i in list1]
print(a)
Output:
[1, 2, 3, nan]
You can easily do that with list comprehension.
a = [i if j == i else np.nan for i in list1 for j in list2]
First we assign i if i==j if it is not we assign np.nan. Then we iterate on list1 for i and list 2 for j
After the if statement of i==j just return another condition after your if statement but on the same indent as your if statement, if will perform that operation in case your if statement is false.
a=[]
for i in list1:
for j in list2:
if i==j:
a.append(i)
a.append(np.nan)
return outside a function or method
i==j fails.
set2 = set(list2); a = [i if i in set2 else 'nan' for i in list1]