Replacing Values in a List with Index in Python

Question

I essentially want to do an Index-Match(think Excel) type formula in Python to replace the None in tuple_list with an the equivalent value in tuple_list1.

My code:

tuple_list =  [("pineapple", 5), ("cherry", 7), ("kumquat", None), ("plum", None)]
tuple_list1 = [("orange, 10"),("plum", 10),("kumquat", 23)]

for item in tuple_list:
    if item[1] == None:
       item[1] = tuple_list[tuple_list1.index(item[0])][1]

print tuple_list

My error:

ValueError: 'kumquat' is not in list

Desired Output:

[("pineapple", 5), ("cherry", 7), ("kumquat", 23), ("plum", 10)]

You have a typo in line 2 of your code. There sould be ("orange", 10) instead of ("orange, 10"). — Nebril
– Nebril, Commented Dec 23, 2014 at 21:30

Nebril · Accepted Answer · 2014-12-23 21:33:07Z

1

You probably should use dictionaries for that, but if you need to use this data format, you need to filter the tuple_list1 to get the data you need.

tuple_list =  [("pineapple", 5), ("cherry", 7), ("kumquat", None), ("plum", None)]
tuple_list1 = [("orange", 10),("plum", 10),("kumquat", 23)]

for key, item in enumerate(tuple_list):
    if item[1] == None:
        tuple_list[key] = (item[0], [x for x in tuple_list1 if x[0] == item[0]][0][1])

print tuple_list

answered Dec 23, 2014 at 21:33

Nebril

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Comments

Coding Orange · Accepted Answer · 2014-12-23 21:32:45Z

0

You got your tuple_list and tuple_list1 reversed. the breaking line should be:

tuple_list1[tuple_list.index(item)][1]

also shouldn't be using [0] on the item, you're not looking for a component of a tuple, you're looking for the index of the whole tuple

Another issue is going to be that you can't modify an element of a tuple. They're immutable. You'll have to create a new tuple and replace the old one

Here's some code that will do what you want it to do:

tuple_list =  [("pineapple", 5), ("cherry", 7), ("kumquat", None), ("plum", None)]
tuple_list1 = [("orange, 10"),("plum", 10),("kumquat", 23)]

for item in tuple_list:
    if item[1] == None:
       ind = tuple_list.index(item)
       ind2 = [i for i in range(len(tuple_list1)) if tuple_list1[i][0] == item[0]][0]
       tuple_list[ind] = (item[0], tuple_list1[ind2][1])

print tuple_list

edited Dec 23, 2014 at 21:32

answered Dec 23, 2014 at 21:23

Coding Orange

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2 Comments

Nebril Over a year ago

This probably won't work. item in your code is not the same tuple that is in tuple_list. You are right about tuple immuatability though.

Coding Orange Over a year ago

item will indeed be exactly the item that is in tuple_list. Just tried it in a python interpreter...

score 0 · Accepted Answer · 2014-12-26 17:04:22Z

0

You can iterate through tuple_list and tuple_list1 and filter out a new list were all the tuples that had the same value by index of 0 in, right there and now. And then replace it in the new list which is still iterating until it is finished.

Heres my soulution. This creates a new list.

tuple_list =  [("pineapple", 5), ("cherry", 7), ("kumquat", None), ("plum", None)]
tuple_list1 = [("orange", 10),("plum", 10),("kumquat", 23)]

tuple_list = [(v1[0], [v2 for v2 in tuple_list1 if v2[0] == v1[0]][0][1]) if v1[1] == None else v1 for v1 in tuple_list]

print tuple_list

edited Dec 26, 2014 at 17:04

answered Dec 23, 2014 at 22:25

user3679917

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