Python：如何按相似键对字典列表进行排序

Question

I have this data and would like to sort them like this

input:

[{'POINT': 0.1}, {'POINT': 0.2}, {'THRESHOLD': 0.1}, {'THRESHOLD': 0.4}, {'INDEX': 0.3}, {'INDEX': 0.9}]

I want the output to be like this

[
{'POINT': 0.1, 'THRESHOLD': 0.1, 'INDEX': 0.3},
{'POINT': 0.2, 'THRESHOLD': 0.4, 'INDEX': 0.9}

I have tried iterating over the list and keeping tracks of the keys but it doesn't seem smart to me.

Answer 1

Assuming I understood the problem setup correctly, you can do this:

pd.DataFrame({k: list(v.dropna()) for k, v in pd.DataFrame(x).items()}).to_dict('records')

This way values are used in the order they appear in, if you want them sorted, use sorted instead of list :

pd.DataFrame({k: sorted(v.dropna()) for k, v in pd.DataFrame(x).items()}).to_dict('records')

Answer 2

In case it does not have to be the list of dictionaries, you can display it in a pandas dataframe. That would also make it easier for you to do any task on your data.

import pandas as pd


l = [{'POINT': 0.1}, {'POINT': 0.2}, {'THRESHOLD': 0.1}, {'THRESHOLD': 0.4}, {'INDEX': 0.3}, {'INDEX': 0.9}]

result_d, keys = {}, []
for d in l:
    key = list(d.keys())[0]
    if key not in keys:
        keys.append(key)
        result_d[key] = []
        for d2 in l:
            key2 = list(d2.keys())[0]
            if key2 == keys[-1]:
                result_d[key].append(d2[key2])

print(result_d)

Output:

{'POINT': [0.1, 0.2], 'THRESHOLD': [0.1, 0.4], 'INDEX': [0.3, 0.9]}

Construct DataFrame from dict:

pd.DataFrame(result_d)

Output:

   POINT  THRESHOLD  INDEX
0    0.1        0.1    0.3
1    0.2        0.4    0.9