BUG: pd.Dataframe.from_dict when first value is a list

[MaddeeRubenson]

Reproducible example:

import pandas as pd

tmp_scen = {'name': 'Current conditions',
 'actionSet': ['not_irrigated', 'cover_crop_none', 'mar_none'],
 'cost': 0.0,
 'totalNitrogen': 9.649798364504209,
 'totalPhosphorus': 2.4570326616674745,
 'sediment': 1.2039077716577735,
 'appliedWater': 11.607623110151138,
 'infiltrationVolume': 0.7424774065057028,
 'acres': 3.382359912104316,
 'irrType': 'not_irrigated'}

good_result = pd.DataFrame.from_dict(tmp_scen, orient = 'index')

tmp_scen = {'actionSet': ['not_irrigated', 'cover_crop_none', 'mar_none'],
 'name': 'Current conditions',
 'cost': 0.0,
 'totalNitrogen': 9.649798364504209,
 'totalPhosphorus': 2.4570326616674745,
 'sediment': 1.2039077716577735,
 'appliedWater': 11.607623110151138,
 'infiltrationVolume': 0.7424774065057028,
 'acres': 3.382359912104316,
 'irrType': 'not_irrigated'}

error_result = pd.DataFrame.from_dict(tmp_scen, orient = 'index')

Problem description

Error when creating a dataframe from a dictionary when the first item in the dictionary is a list. See reproducible example above.

TypeError: object of type 'float' has no len()

Expected Output

Out[369]: 
                                                             0
actionSet           [not_irrigated, cover_crop_none, mar_none]
name                                        Current conditions
cost                                                         0
totalNitrogen                                           9.6498
totalPhosphorus                                        2.45703
sediment                                               1.20391
appliedWater                                           11.6076
infiltrationVolume                                    0.742477
acres                                                  3.38236
irrType                                          not_irrigated

Output of pd.show_versions()

INSTALLED VERSIONS

commit: None
python: 3.7.3.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel
byteorder: little
LC_ALL: None
LANG: en
LOCALE: None.None

pandas: 0.24.2
pytest: 4.4.1
pip: 19.0.3
setuptools: 40.8.0
Cython: 0.29.6
numpy: 1.16.2
scipy: 1.2.1
pyarrow: None
xarray: None
IPython: 7.4.0
sphinx: 1.8.5
patsy: 0.5.1
dateutil: 2.8.0
pytz: 2018.9
blosc: None
bottleneck: 1.2.1
tables: 3.5.1
numexpr: 2.6.9
feather: None
matplotlib: 3.0.3
openpyxl: 2.6.1
xlrd: 1.2.0
xlwt: 1.3.0
xlsxwriter: 1.1.5
lxml.etree: 4.3.2
bs4: 4.7.1
html5lib: 1.0.1
sqlalchemy: 1.3.1
pymysql: 0.9.3
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
gcsfs: None

[WillAyd]

This seems to work fine on master, though not with the result you would expect. It is ambiguous as to whether you mean to get a 1 column data frame or a 3 column data frame and just made a programming mistake with this kind of construction.

Not sure if there is anything to do here. Note you can construct a Series instead if you want 1D

[asishm]

@WillAyd both examples use the same dictionary albeit with a different order of keys.

Edit: a simpler example:

In [25]: pd.DataFrame.from_dict({'a': [1,2,3], 'b': 1}, orient='index')
# TypeError: object of type 'int' has no len()
In [26]: pd.DataFrame.from_dict({'b': 1, 'a': [1,2,3]}, orient='index')
Out[26]:
           0
b          1
a  [1, 2, 3]

Note that the initial object itself is the same in both examples. Python dicts aren't guaranteed insertion order until 3.7 (iirc).

[matttan90]

Hey! I'm having a go at this.

[Dr4cky]

Wow, I did not think changing the order would fix my issue, but it did. Having a list as the very first value in a dictionary gave me the 'object of type 'float' has no len()' error.