how to delete item from a list of key-value pairs in python

Question

I have a list of key-value pair in python. A sample of this list is:

list_pairs = [{'text': 'Zen', 'value': 'Zen'}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]

Now I have a string str1 and what I want to do is to match it with text field of each key-value pair and delete the one which matches. So if my string is Zen then delete {'text': 'Zen', 'value': 'Zen'} from the list.

I tried to do del list_pairs[str1] but it throws error as list indices can only be integers and not str.

How can I delete the items from my list of key-value pair?

You have a `list` with `dict` objects. You need to use integer indices to access the `list` items, or iterate over it directly `for d in list_pairs: ...` then you can index into the `dict` objects with strings, i.e. `d['text'] == 'Zen'`. — juanpa.arrivillaga, Feb 23 '18 at 18:52
You have a list of dicts NOT "key-value" pairs, there's a difference — smac89, Feb 23 '18 at 19:26

skmth · Answer 1 · 2018-02-23T19:35:15.477

4

True @smac89. Concise answer would be :

new_list_pair = [d for d in list_pairs if d['text'] != str1]

Thanks @ juanpa.arrivillaga

Not recommend incorrect version:

str1 = 'Zen'
for d in list_pairs:
    if d['text'] == str1:
        list_pairs.remove(d)

edited Feb 23 '18 at 19:35

answered Feb 23 '18 at 18:54

skmth

164
6

1

You can easily turn this into list comprehension – smac89 Feb 23 '18 at 18:59
You are unsafely removing from a list while iterating over it – juanpa.arrivillaga Feb 23 '18 at 19:05
Your concise version is what I would recommend. Don't mess with a list as you iterate through it, just create a new one. – Aphid Feb 23 '18 at 19:09
1

Note, the two versions are *not equivalent*, and your second version is still incorrect. – juanpa.arrivillaga Feb 23 '18 at 19:11
Also, using `list.remove` here is very inefficient, since it will iterate from the beginning of the list checking equality for each element until it finds one, but you already know the element you want to remove.. – juanpa.arrivillaga Feb 23 '18 at 19:18

PythonProgrammi · Accepted Answer · 2018-03-28T06:52:12.160

Delete

l = [{'text': 'Zen', 'value': 'Zen'}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]

collect = []
for n, d in enumerate(l):
    for k in d:
        if d[k] == 'Zen':
            print(k)
            collect.append([n, k])

for v in collect:
    del l[v[0]][v[1]]

print(l)

out:

text
value
[{}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]

List comprehension

l = [{'text': 'Zen', 'value': 'Zen'}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]

collect = []
[[collect.append([n, k]) for k in d if d[k] == "Zen"] for n, d in enumerate(l)]

for v in collect:
    del l[v[0]][v[1]]

print(l)

out:

[{}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]

Aparna Chaganti · Answer 3 · 2018-02-23T19:18:17.917

0

def del_match(str):
     for index,item in enumerate(list_pairs):
         if item['text'] is str:
             del list_pairs[index]

I am leaving this bad answer here, please refer to the comments below on why it is a bad answer, may be it will help people to get more out of this problem.

edited Feb 23 '18 at 19:18

answered Feb 23 '18 at 18:56

Aparna Chaganti

599
2
5
15

You are unsafely removing from a list while iterating over it – juanpa.arrivillaga Feb 23 '18 at 19:04
Thanks, what are the implications of doing so ? – Aparna Chaganti Feb 23 '18 at 19:14
You will skip items. See [this question](https://stackoverflow.com/questions/6260089/strange-result-when-removing-item-from-a-list?noredirect=1&lq=1) – juanpa.arrivillaga Feb 23 '18 at 19:15
2

So, try this on the following data: `[{'text': 'Zen', 'value': 'Zen'}, {'text': 'Zen', 'value': 'Zen'}, {'text': 'Global', 'value': 'Global'}, {'text': 'Corporation', 'value': 'Corporation'}]` – juanpa.arrivillaga Feb 23 '18 at 19:16
1

You can simply iterate over a copy for a quick fix, i.e. do `for i, item in enumerate(list_pairs[:])` – juanpa.arrivillaga Feb 23 '18 at 19:19

how to delete item from a list of key-value pairs in python

3 Answers3

Delete

out:

List comprehension

out: