BUG: dataframe.eval() throws error when using @function if numexpr package is installed

[bogdanCsn]

Full details and workaround are available in this SO question

Code Sample, a copy-pastable example if possible

import numpy as np
import pandas as pd
from numpy import around

df = pd.DataFrame({'x':np.array([1.12,2.76])})

# this throws TypeError: 'Series' objects are mutable, thus they cannot be hashed
df['y'] = df.eval('@around(x,1)')

Problem description

The evaluated expression should work because around is imported into the local namespace. There are two solutions:

• remove numexpr from the environment.
• set the engine for parsing the expression to be python:

df['y'] = df.eval('@around(x,1)', engine = 'python')

Expected Output

          x    y
0  1.133320  1.1
1  2.733336  2.7

Output of pd.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.7.0.final.0 python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 58 Stepping 9, GenuineIntel byteorder: little LC_ALL: None LANG: en LOCALE: None.None

pandas: 0.23.4
pytest: None
pip: 10.0.1
setuptools: 40.2.0
Cython: None
numpy: 1.15.1
scipy: 1.1.0
pyarrow: None
xarray: None
IPython: 6.5.0
sphinx: 1.7.8
patsy: None
dateutil: 2.7.3
pytz: 2018.5
blosc: None
bottleneck: None
tables: None
numexpr: 2.6.8
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: 1.0.1
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

[jreback]

this has nothing to with an import from the local name space or not
eval doesn’t support in line function evaluation

this is a duplicate issue as well

[bogdanCsn]

@jreback Eval does support in line function evaluation.
I edited my first post to show that there actually is a better solution - specify the parsing engine to be python, no need to remove numexpr from the environment. Running df['y'] = df.eval('@around(x,1)', engine = 'python') produces the expected output.

I'm not sure this is a bug anymore, the workaround to the original issue is trivial.

[gfyoung]

this is a duplicate issue as well

@jreback : I'm not entirely sure which issue this duplicates, so labeling for now. Given that the code works with engine='python', is that just coincidental?