当值为零时如何使用枚举跳过索引计数？

Question

I have currently one dict with key-value and one list with values. eg

data = {
    'total': {
        '06724': 0,
        '06725': 0,
        '06726': 0,
        '06727': 0,
        '06712': 22,
        '06713': 35,
        '06714': 108,
        '06715': 70,
        '06716': 0,
        '06717': 24,
        '06718': 0,
        '06719': 0,
        '06720': 0,
        '06709': 75,
        '06710': 123,
        '06711': 224,
        '06708': 28,
        '06723': 0,
        '06721': 0,
        '06722': 0
    },
    'item_number': ['1', '2', '3', '4', '5', '6', '7', '8', '9']
}

for Index, value in enumerate(data['total'].values()):
    if value and value != '0':
        print(data['item_number'][Index], value)

What I am trying to do is that I want to remove all values in 'total' that has the value 0 meaning that it would only end up being 9 numbers which adds up to the item_number amount.

What I am trying to achieve is that I want print out:

Expected :

{
    '1': 22,
    '2': 35,
    '3': 108,
    '4': 70,
    '5': 24,
    '6': 75,
    '7': 123,
    '8': 224,
    '9': 28
}

where key is the item_number and the value is total .

However the code I am currently trying gives me the error:

    print(data['item_number'][Index], value)
IndexError: list index out of range

which I believe is due to the Index increasing for each loop. I wonder how can I skip the counting increase if the value is 0?

Answer 1

If I understand you correctly:

out = dict(
    zip(data["item_number"], (v for v in data["total"].values() if v != 0))
)
print(out)

Prints:

{
    "1": 22,
    "2": 35,
    "3": 108,
    "4": 70,
    "5": 24,
    "6": 75,
    "7": 123,
    "8": 224,
    "9": 28,
}

Answer 2

Either use a count variable instead of enumerate() , or filter before enumerating.

Count variable

index = 0
for value in data['total'].values():
    if value != 0:
        print((data['item_number'][index], value))
        index += 1

Output:

('1', 22)
('2', 35)
('3', 108)
('4', 70)
('5', 24)
('6', 75)
('7', 123)
('8', 224)
('9', 28)

Filter first

for index, value in enumerate(v for v in data['total'].values() if v != 0):
    print((data['item_number'][index], value))

(Same output)

And this can be simplified further using zip() like in Andrej's answer .

---

Note : I'm not using a dict here for simplicity and because your code as posted doesn't use one. I think it's obvious how you would incorporate one though.

Answer 3

There are two tasks at hand here:

1. Filter out the zero values from data["total"]
2. Create a dictionary, where keys are the elements of data["item_number"] , and values are from the filtered collection we created above.

So, let's do that:

filtered_values = [val for val in data["total"].values() if val]
# [22, 35, 108, 70, 24, 75, 123, 224, 28]

new_dict = dict(zip(data["item_number"], filtered_values))

Which gives the required new_dict :

{'1': 22,
 '2': 35,
 '3': 108,
 '4': 70,
 '5': 24,
 '6': 75,
 '7': 123,
 '8': 224,
 '9': 28}

You can save one loop through your data["total"] if you define filtered_values as a generator expression, or combine the two lines:

new_dict = dict(zip(data["item_number"], (val for val in data["total"].values() if val)))