from_records should order dict columns similar to constructor and from_dict like pandas < 0.23

[llawall]

Code Sample, a copy-pastable example if possible

import pandas as pd

print("Pandas version :  ", pd.__version__)

def print_dict(fn):
    print(fn.__name__)
    print(fn(dict(C=[3], B=[2], A=[1])))

with pd.option_context('display.max_rows', 10, 'display.max_columns', 5):
    print_dict(pd.DataFrame)
    print_dict(pd.DataFrame.from_dict)
    print_dict(pd.DataFrame.from_records)

Problem description

pandas 0.22 gave consistent output when creating a DataFrame passing a dictionary using any of DataFrame constructor, DataFrame.from_dict and DataFrame.from_records. pandas 0.23 changed the behaviour of creating from dictionaries to respect key ordering in Python version 3.6+ for both the DataFrame constructor and DataFrame.from_dict but not using DataFrame.from_records.

Output 0.23

Different ordering of columns depending on construction method

Pandas version :   0.23.4
DataFrame
   C  B  A
0  3  2  1
from_dict
   C  B  A
0  3  2  1
from_records
   A  B  C
0  1  2  3

Output 0.22

Consistent ordering of columns (sorted keys)

Pandas version :   0.22.0
DataFrame
   A  B  C
0  1  2  3
from_dict
   A  B  C
0  1  2  3
from_records
   A  B  C
0  1  2  3

Expected Output (my local build including #22687)

Consistent ordering of columns (dict key order respected)

Pandas version :   0.24.0.dev0+570.g434910bcb
DataFrame
   C  B  A
0  3  2  1
from_dict
   C  B  A
0  3  2  1
from_records
   C  B  A
0  3  2  1

[TomAugspurger]

I'm not quite sure I understand what you mean by "dicts of different orders in records"?

For example, what's the order of

pd.DataFrame.from_records([{'b': 1, 'a': 2}, {'a': 2, 'b': 1}])

[llawall]

@TomAugspurger My change does not change the current behaviour in that example. The code path in that case is pandas.core.frame#1315 which ultimately calls through to _list_of_dict_to_arrays.

[llawall]

I've pushed a test for this that shows the changed behaviour making from_records consistent with the DataFrame constructor when only a single dictionary is passed as input.