python: using Jupyter notebook (testing matplotlib and opencv)

environment:

• window1
• python 3.10.6

reference:

• https://jupyter.org/
• https://opencv.org/

1. Create a virtual environment

This step can be skipped (because the author doesn't like to install anything in the global environment, so make a new environment).

First select a directory: D:\jackletter\test-pyenv(This directory has not been created yet)
Enter powershell:

Execute the command:py -m venv test-pyenv

Activate the environment:.\test-pyenv\Scripts\Activate.ps1

2. Install Jupyter notebook

implementpip install notebook

After the installation is complete, you will see the following (pip list shows that there are many more packages):

3. Use Jupyter notebook

First select an empty directory, as follows:

The command line is positioned here, and then executed: jupyter notebook

At this point we can create a new test (ctrl+enter to execute the code):

4. Test matplotlib

First install: pip install matplotlib, check the version after installation (pip list):

Then test in Jupyter notebook as follows:

import matplotlib.pyplot as plt
x = [1, 2, 3, 4]
y = [2, 4, 2, 6]
y1 = [e+1 for e in y]
y2 = [e+2 for e in y]
plt.plot(x, y, "b.")                  # b：蓝色，.：点
plt.plot(x, y1, "ro")                  # r：红色，o：圆圈
plt.plot(x, y2, "kx")                 # k：黑色，x：x字符(小叉)
plt.show()                            # 在窗口显示该图片

5. Test opencv

Or install first, pip install opencv-pythonand check the version after installation (pip list):

Then, prepare an image in the Jupyter notebook directory:

Then test in Jupyter notebook as follows:

import cv2

img = cv2.imread('cat.webp')

cv2.imshow('cat',img)

cv2.waitKey(0)