From 4eeda0554ec1eacffba45e01b08e372ffa7bf656 Mon Sep 17 00:00:00 2001 From: DarkSun Date: Tue, 14 Sep 2021 05:04:21 +0800 Subject: [PATCH] =?UTF-8?q?=E9=80=89=E9=A2=98[tech]:=2020210913=20How=20I?= =?UTF-8?q?=20rediscovered=20Logo=20with=20the=20Python=20Turtle=20module?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sources/tech/20210913 How I rediscovered Logo with the Python Turtle module.md --- ...ered Logo with the Python Turtle module.md | 327 ++++++++++++++++++ 1 file changed, 327 insertions(+) create mode 100644 sources/tech/20210913 How I rediscovered Logo with the Python Turtle module.md diff --git a/sources/tech/20210913 How I rediscovered Logo with the Python Turtle module.md b/sources/tech/20210913 How I rediscovered Logo with the Python Turtle module.md new file mode 100644 index 0000000000..8a3bee24a5 --- /dev/null +++ b/sources/tech/20210913 How I rediscovered Logo with the Python Turtle module.md @@ -0,0 +1,327 @@ +[#]: subject: "How I rediscovered Logo with the Python Turtle module" +[#]: via: "https://opensource.com/article/21/9/logo-python-turtle" +[#]: author: "Ayush Sharma https://opensource.com/users/ayushsharma" +[#]: collector: "lujun9972" +[#]: translator: " " +[#]: reviewer: " " +[#]: publisher: " " +[#]: url: " " + +How I rediscovered Logo with the Python Turtle module +====== +The Logo programming language is available today as a Python package. +![Box turtle][1] + +When I was in high school, one of the very first programming languages I was introduced to was Logo. It was interactive and visual. With basic movement commands, you could have your cursor (“turtle”) draw basic shapes and intricate patterns. It was a great way to introduce the compelling concept of an algorithm—a series of instructions for a computer to execute. + +Fortunately, the Logo programming language is available today as a Python package. So let’s jump right in, and you can discover the possibilities with Logo as we go along. + +### Installing the Turtle module + +Logo is available as the [`turtle` package for Python][2]. To use it, you must have Python installed first. Python is already installed on Linux and BSD, and it's easy to install on both [MacOS][3] and [Windows][4]. + +Once you have Python installed, install the Turtle module: + + +``` +`pip3 install turtle` +``` + +### Bob draws a square + +With the `turtle` package installed, you can draw some basic shapes. + +To draw a square, imagine a turtle (call him Bob) in the middle of your screen, holding a pen with his tail. Every time Bob moves, he draws a line behind him. How must Bob move to draw a square? + + 1. Move forward 100 steps. + 2. Turn right 90 degrees. + 3. Move forward 100 steps. + 4. Turn right 90 degrees. + 5. Move forward 100 steps. + 6. Turn right 90 degrees. + 7. Move forward 100 steps. + + + +Now write the above algorithm in Python. Create a file called `logo.py` and place the following code in it. + + +``` +import turtle + +if __name__ == '__main__': + +    turtle.title('Hi! I\'m Bob the turtle!') +    turtle.setup(width=800, height=800) + +    bob = turtle.Turtle(shape='turtle') +    bob.color('orange') + +    # Drawing a square +    bob.forward(100) +    bob.right(90) +    bob.forward(100) +    bob.right(90) +    bob.forward(100) +    bob.right(90) +    bob.forward(100) + +    turtle.exitonclick() +``` + +Save the above as `logo.py` and run it: + + +``` +`$ python3 logo.py` +``` + +Bob draws a square on the screen: + +![Logo drawn square][5] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +### Bob draws a hexagon + +To draw a hexagon, Bob must move like this: + + 1. Move forward 150 steps. + 2. Turn right 60 degrees. + 3. Move forward 150 steps. + 4. Turn right 60 degrees. + 5. Move forward 150 steps. + 6. Turn right 60 degrees. + 7. Move forward 150 steps. + 8. Turn right 60 degrees. + 9. Move forward 150 steps. + 10. Turn right 60 degrees. + 11. Move forward 150 steps. + + + +In Python, you can use a [`for` loop][7] to move Bob: + + +``` +import turtle + +if __name__ == '__main__': + +    turtle.title('Hi! I\'m Bob the turtle!') +    turtle.setup(width=800, height=800) + +    bob = turtle.Turtle(shape='turtle') +    bob.color('orange') + +    # Drawing a hexagon +    for i in range(6): + +        bob.forward(150) +        bob.right(60) + +    turtle.exitonclick() +``` + +Run your code again and watch Bob draw a hexagon. + +![Logo drawn hexagon][8] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +### Bob draws a square spiral + +Now try drawing a square spiral, but this time you can speed things up a bit. You can use the `speed` function and set `bob.speed(2000)` so that Bob moves faster. + + +``` +import turtle + +if __name__ == '__main__': + +    turtle.title('Hi! I\'m Bob the turtle!') +    turtle.setup(width=800, height=800) + +    bob = turtle.Turtle(shape='turtle') +    bob.color('orange') + +    # Drawing a square spiral +    bob.speed(2000) +    for i in range(500): + +        bob.forward(i) +        bob.left(91) + +    turtle.exitonclick() +``` + +![Logo drawn spiral][9] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +### Bob and Larry draw a weird snake thing + +In the above examples, you initialized `Bob` as an object of the `Turtle` class. You're not limited to just one turtle, though. In the next code block, create a second turtle called `Larry` to draw along with Bob. + +The `penup()` function makes the turtles lift their pens, so they don’t draw anything as they move, and the `stamp()` function places a marker whenever it’s called. + + +``` +import turtle + +if __name__ == '__main__': + +    turtle.title('Hi! We\'re Bob and Larry!') +    turtle.setup(width=800, height=800) + +    bob = turtle.Turtle(shape='turtle') +    larry = turtle.Turtle(shape='turtle') +    bob.color('orange') +    larry.color('purple') + +    bob.penup() +    larry.penup() +    bob.goto(-180, 200) +    larry.goto(-150, 200) +    for i in range(30, -30, -1): + +        bob.stamp() +        larry.stamp() +        bob.right(i) +        larry.right(i) +        bob.forward(20) +        larry.forward(20) + +    turtle.exitonclick() +``` + +![Logo drawn snake][10] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +### Bob draws a sunburst + +Bob can also draw simple lines and fill them in with color. The functions `begin_fill()` and `end_fill()` allow Bob to fill a shape with the color set with `fillcolor()`. + + +``` +import turtle + +if __name__ == '__main__': + +    turtle.title('Hi! I\'m Bob the turtle!') +    turtle.setup(width=800, height=800) + +    bob = turtle.Turtle(shape='turtle') +    bob.color('orange') + +    # Drawing a filled star thingy +    bob.speed(2000) +    bob.fillcolor('yellow') +    bob.pencolor('red') + +    for i in range(200): + +        bob.begin_fill() +        bob.forward(300 - i) +        bob.left(170) +        bob.forward(300 - i) +        bob.end_fill() + +    turtle.exitonclick() +``` + +![Logo drawn sunburst][11] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +### Larry draws a Sierpinski triangle + +Bob enjoys drawing simple geometrical shapes holding a pen with his tail as much as the next turtle, but what he enjoys most is drawing fractals. + +One such shape is the [Sierpinski triangle][12], which is an equilateral triangle recursively subdivided into smaller equilateral triangles. It looks something like this: + +![Logo drawn triangle][13] + +Illustration by Ayush Sharma, [CC BY-SA 4.0][6] + +To draw the Sierpinski triangle above, Bob has to work a bit harder: + + +``` +import turtle + +def get_mid_point(point_1: list, point_2: list): + +    return ((point_1[0] + point_2[0]) / 2, (point_1[1] + point_2[1]) / 2) + +def triangle(turtle: turtle, points, depth): + +    turtle.penup() +    turtle.goto(points[0][0], points[0][1]) + +    turtle.pendown() +    turtle.goto(points[1][0], points[1][1]) +    turtle.goto(points[2][0], points[2][1]) +    turtle.goto(points[0][0], points[0][1]) + +    if depth > 0: + +        triangle(turtle, [points[0], get_mid_point(points[0], points[1]), get_mid_point(points[0], points[2])], depth-1) +        triangle(turtle, [points[1], get_mid_point(points[0], points[1]), get_mid_point(points[1], points[2])], depth-1) +        triangle(turtle, [points[2], get_mid_point(points[2], points[1]), get_mid_point(points[0], points[2])], depth-1) + +if __name__ == '__main__': + +    turtle.title('Hi! I\'m Bob the turtle!') +    turtle.setup(width=800, height=800) + +    larry = turtle.Turtle(shape='turtle') +    larry.color('purple') + +    points = [[-175, -125], [0, 175], [175, -125]]  # size of triangle + +    triangle(larry, points, 5) + +    turtle.exitonclick() +``` + +### Wrap up + +The Logo programming language is a great way to teach basic programming concepts, such as how a computer can execute a set of commands. Also, because the library is now available in Python, it can be used to visualize complex ideas and concepts. + +I hope Bob and Larry have been enjoyable and instructive. + +Have fun, and happy coding. + +* * * + +_This article was originally published on the [author's personal blog][14] and has been adapted with permission._ + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/21/9/logo-python-turtle + +作者：[Ayush Sharma][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/ayushsharma +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/patti-black-unsplash.jpg?itok=hS8wQNUg (Box turtle) +[2]: https://docs.python.org/3.7/library/turtle.html +[3]: https://opensource.com/article/19/5/python-3-default-mac +[4]: https://opensource.com/article/19/8/how-install-python-windows +[5]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-square.jpg (Logo drawn square) +[6]: https://creativecommons.org/licenses/by-sa/4.0/ +[7]: https://opensource.com/article/18/3/loop-better-deeper-look-iteration-python +[8]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-hexagon.jpg (Logo drawn hexagon) +[9]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-square-spiral.jpg (Logo drawn spiral) +[10]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-stamping-larry.jpg (Logo drawn snake) +[11]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-sunburst.jpg (Logo drawn sunburst) +[12]: https://en.wikipedia.org/wiki/Sierpinski_triangle +[13]: https://opensource.com/sites/default/files/uploads/rediscovering-logo-python-turtle-sierpinski-triangle.jpg (Logo drawn triangle) +[14]: https://notes.ayushsharma.in/2019/06/rediscovering-logo-with-bob-the-turtle