如何将不对称的成对距离矩阵转换为字典？

Question

I've distance matrix which I want to convert to a dict with two keys and one value. My csv file looks something like this:

	City1	City2	City3
City1	0	2.2	3.1
City2	2.1	0	4.0
City3	3.2	4.3	0

And I imported my csv file as a pandas data frame with pd.read_csv and now I want to convert this data frame to a dictionary which should use the first column and the first row as keys and the rest as values. So like:

{('City1','City1'): 0, ('City1','City2'): 2.1, ('City1','City3'): 3.2, ...}

I tried to use pandas.to_dict function but I wasn't able to figure out how to tell this function to not only use the column names as the keys. Thank you in advance.

Answer 1

Let's try stack then to_dict:

import pandas as pd

df = pd.DataFrame({
    'City1': {'City1': 0, 'City2': 2.1, 'City3': 3.2},
    'City2': {'City1': 2.2, 'City2': 0.0, 'City3': 4.2},
    'City3': {'City1': 3.1, 'City2': 4.0, 'City3': 0},
})

d = df.stack().to_dict()
print(d)

df :

       City1  City2  City3
City1    0.0    2.2    3.1
City2    2.1    0.0    4.0
City3    3.2    4.2    0.0

d :

{('City1', 'City1'): 0.0, ('City1', 'City2'): 2.2, ('City1', 'City3'): 3.1,
 ('City2', 'City1'): 2.1, ('City2', 'City2'): 0.0, ('City2', 'City3'): 4.0,
 ('City3', 'City1'): 3.2, ('City3', 'City2'): 4.2, ('City3', 'City3'): 0.0}