带有Matplotlib (或Numpy，或Plotly)的烧瓶- ModuleNotFound

Question

我正在尝试在我的SQL支持的烧瓶应用程序中尝试使用matplotlib图表，但是当我试图导入它时，我得到了ModuleNotFound错误。注意，在尝试导入numpy或巧妙地表示时，我也会得到相同的错误。不过，我的venv能够识别SQLAlchemy库，所以我不确定发生了什么。如有任何建议，将不胜感激。

复制的最小步骤：

mkdir flask_test
cd flask_test
python3 -m venv venv
. venv/bin/activate

用pip list快速检查预安装

Package    Version
---------- -------
pip        21.3.1
setuptools 60.5.0
WARNING: You are using pip version 21.3.1; however, version 22.0.4 is available.
You should consider upgrading via the '/Users/<me>/Desktop/flask_test/venv/bin/python3.9 -m pip install --upgrade pip' command.

继续安装：

pip install Flask SQLAlchemy matplotlib

  Using cached Flask-2.1.1-py3-none-any.whl (95 kB)
Collecting SQLAlchemy
  Using cached SQLAlchemy-1.4.35-cp39-cp39-macosx_10_15_x86_64.whl (1.5 MB)
Collecting matplotlib
  Using cached matplotlib-3.5.1-cp39-cp39-macosx_10_9_x86_64.whl (7.3 MB)
Collecting importlib-metadata>=3.6.0
  Using cached importlib_metadata-4.11.3-py3-none-any.whl (18 kB)
Collecting Werkzeug>=2.0
  Using cached Werkzeug-2.1.1-py3-none-any.whl (224 kB)
Collecting click>=8.0
  Using cached click-8.1.2-py3-none-any.whl (96 kB)
Collecting Jinja2>=3.0
  Using cached Jinja2-3.1.1-py3-none-any.whl (132 kB)
Collecting itsdangerous>=2.0
  Using cached itsdangerous-2.1.2-py3-none-any.whl (15 kB)
Collecting greenlet!=0.4.17
  Using cached greenlet-1.1.2-cp39-cp39-macosx_10_14_x86_64.whl (92 kB)
Collecting packaging>=20.0
  Using cached packaging-21.3-py3-none-any.whl (40 kB)
Collecting python-dateutil>=2.7
  Using cached python_dateutil-2.8.2-py2.py3-none-any.whl (247 kB)
Collecting pillow>=6.2.0
  Using cached Pillow-9.1.0-cp39-cp39-macosx_10_9_x86_64.whl (3.1 MB)
Collecting pyparsing>=2.2.1
  Using cached pyparsing-3.0.8-py3-none-any.whl (98 kB)
Collecting numpy>=1.17
  Using cached numpy-1.22.3-cp39-cp39-macosx_10_14_x86_64.whl (17.6 MB)
Collecting kiwisolver>=1.0.1
  Using cached kiwisolver-1.4.2-cp39-cp39-macosx_10_9_x86_64.whl (65 kB)
Collecting cycler>=0.10
  Using cached cycler-0.11.0-py3-none-any.whl (6.4 kB)
Collecting fonttools>=4.22.0
  Using cached fonttools-4.32.0-py3-none-any.whl (900 kB)
Collecting zipp>=0.5
  Using cached zipp-3.8.0-py3-none-any.whl (5.4 kB)
Collecting MarkupSafe>=2.0
  Using cached MarkupSafe-2.1.1-cp39-cp39-macosx_10_9_x86_64.whl (13 kB)
Collecting six>=1.5
  Using cached six-1.16.0-py2.py3-none-any.whl (11 kB)
Installing collected packages: zipp, Werkzeug, six, pyparsing, pillow, numpy, MarkupSafe, kiwisolver, itsdangerous, greenlet, fonttools, cycler, click, SQLAlchemy, python-dateutil, packaging, Jinja2, importlib-metadata, matplotlib, Flask
Successfully installed Flask-2.1.1 Jinja2-3.1.1 MarkupSafe-2.1.1 SQLAlchemy-1.4.35 Werkzeug-2.1.1 click-8.1.2 cycler-0.11.0 fonttools-4.32.0 greenlet-1.1.2 importlib-metadata-4.11.3 itsdangerous-2.1.2 kiwisolver-1.4.2 matplotlib-3.5.1 numpy-1.22.3 packaging-21.3 pillow-9.1.0 pyparsing-3.0.8 python-dateutil-2.8.2 six-1.16.0 zipp-3.8.0

退出venv deactivate

创建hello.py应用程序(hello.py)，每个瓶子快速启动：

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"

运行它

export FLASK_APP=hello
export FLASK_ENV=development
flask run

它运行的很好，我可以看到你好世界。

 * Serving Flask app 'hello' (lazy loading)
 * Environment: development
 * Debug mode: on
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 687-225-XXX

现在我尝试导入SQLAlchemy：

from flask import Flask
from sqlalchemy import inspect

app = Flask(__name__)

@app.route("/")
def hello_world():
    print(inspect)
    return "<p>Hello, World!</p>"

我可以看到控制台中正在打印in对象：

<function inspect at 0x10e999ee0>

现在尝试导入matplotlib：

from flask import Flask
from sqlalchemy import inspect
import matplotlib.pyplot as plt

app = Flask(__name__)

@app.route("/")
def hello_world():
    print(inspect)
    print(plt)
    return "<p>Hello, World!</p>"

当我得到这个错误时：

flask.cli.NoAppException: While importing 'hello', an ImportError was raised:

Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/flask/cli.py", line 260, in locate_app
__import__(module_name)
File "/Users/<me>/Desktop/flask_test/hello.py", line 3, in <module>
import matplotlib.pyplot as plt
ModuleNotFoundError: No module named 'matplotlib'

Answer 1

为了将来的参考：

似乎Flask和SqlAlchemy都安装了系统级，从而给人一种错误的印象，认为matplotlib安装出了问题。

有几种选择：

1. 启动虚拟主机，然后运行烧瓶。即. ./venv/bin/activate FLASK_APP=hello FLASK_ENV=development flask run

FLASK_APP=hello FLASK_ENV=development ./venv/bin/flask run

1. 直接运行烧瓶二进制文件

completeness)

1. 安装matplotlib系统级别(不是真正推荐的)，只是为添加以下内容

既然您已经创建了虚拟环境，请使用选项1。