CODEWITHSUNDEEP
pythonlistnumpy
Dong-gyun Kim
Dong-gyun Kim

Reputation: 431

insert value in a list ignoring nan

How to insert a value right before the nan in a list having nan at the end of the list?

random = [9,1,5, ... 7,6,3,2,5, nan, nan, nan, ...]

random.append(8181) < somehow add function here

results should be, the value inserted before first nan

random = [9,1,5, ... 7,6,3,2,5,8181, nan, nan, nan, ...]

Upvotes: 1

Views: 490

Answers (2)

TheLazyScripter
TheLazyScripter

Reputation: 2665

If we know how many NaN values we have then we can use insert with a negative count.

my_list.insert(-nan_count, 8181)

If we don't know the count, then we need to find out the last position.

for i,v in enumerate(reversed(my_list)): # loop backwards
    if v==v:
        a.insert(len(a)-i, 8181) # found the first non NaN, insert just before this
        break # only do it for the first item

Upvotes: 1

wim
wim

Reputation: 362627

Traverse the list from end to find the correct position, then use list.insert:

import math

i = 0
while math.isnan(random[i - 1]):
    i -= 1

random.insert(i, 8181)

Upvotes: 3

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