症状

Code セル

import pandas as pd

実行結果

ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-2-ca154c91f1ef> in <module>
----> 1 import pandas as pd
      2 

ModuleNotFoundError: No module named 'pandas'

調査

JupyterLab のパスを調べる

Code セル

import sys
import pprint

pprint.pprint(sys.path)

実行結果

['/Users/oppara/sandbox/jupterlab',
 '/usr/local/Cellar/jupyterlab/1.2.4/libexec/lib/python37.zip',
 '/usr/local/Cellar/jupyterlab/1.2.4/libexec/lib/python3.7',
 '/usr/local/Cellar/jupyterlab/1.2.4/libexec/lib/python3.7/lib-dynload',
 '/usr/local/opt/python/Frameworks/Python.framework/Versions/3.7/lib/python3.7',
 '',
 '/usr/local/Cellar/jupyterlab/1.2.4/libexec/lib/python3.7/site-packages',
 '/usr/local/Cellar/jupyterlab/1.2.4/libexec/lib/python3.7/site-packages/IPython/extensions',
 '/Users/oppara/.ipython']

pandas のパスを確認

% pip3 show pandas
Name: pandas
Version: 1.0.1
Summary: Powerful data structures for data analysis, time series, and statistics
Home-page: https://pandas.pydata.org
Author: None
Author-email: None
License: BSD
Location: /usr/local/lib/python3.7/site-packages
Requires: numpy, pytz, python-dateutil
Required-by:

原因

pandas がインストールされているパスが、JupyterLab のパスに含まれていない。

力技な対応

Code セル

import sys
sys.path.append('/usr/local/lib/python3.7/site-packages')

import pandas as pd

その他の対応

Homebrew でなく、pip(pip3) でインストールした JupyterLab を使う

% brew uninstall jupyterlab
% pip3 install jupyterlab

pip でインストールした JupyterLab のパス

['/Users/oppara/sandbox/jupterlab',
 '/usr/local/Cellar/python/3.7.6_1/Frameworks/Python.framework/Versions/3.7/lib/python37.zip',
 '/usr/local/Cellar/python/3.7.6_1/Frameworks/Python.framework/Versions/3.7/lib/python3.7',
 '/usr/local/Cellar/python/3.7.6_1/Frameworks/Python.framework/Versions/3.7/lib/python3.7/lib-dynload',
 '',
 '/Users/oppara/Library/Python/3.7/lib/python/site-packages',
 '/usr/local/lib/python3.7/site-packages',
 '/usr/local/Cellar/protobuf/3.11.3/libexec/lib/python3.7/site-packages',
 '/usr/local/lib/python3.7/site-packages/IPython/extensions',
 '/Users/oppara/.ipython']

環境

% sw_vers
ProductName:    Mac OS X
ProductVersion: 10.15.3
BuildVersion:   19D7

% brew --version
Homebrew 2.2.5

% python3 -V
Python 3.7.6

参照

Jupyter Notebook: ModuleNotFoundError: No module named 'pandas' - Qiita