2018年4月18日水曜日

開発環境

Pythonからはじめる数学入門 (Amit Saha (著)、黒川 利明 (翻訳)、オライリージャパン)の2章(データをグラフで可視化する)、2.6(プログラミングチャレンジ)、問題2-3(投射軌跡比較プログラムの拡張)を取り組んでみる。

コード(Emacs)

Python 3

#!/usr/bin/env python3

import math
from matplotlib import pyplot as plt


def draw_graph(x, y):
    plt.plot(x, y)
    plt.xlabel('x-coordinate')
    plt.ylabel('y-coordinate')
    plt.title('Projectile motion of a ball')


def frange(start, final, interval):
    numbers = []
    while start < final:
        numbers.append(start)
        start += interval
    return numbers


def draw_trajectory(u, theta):
    theta = math.radians(theta)
    g = 9.8
    t_flight = 2 * u * math.sin(theta) / g
    intervals = frange(0, t_flight, 0.001)
    x = []
    y = []
    for t in intervals:
        x.append(u * math.cos(theta) * t)
        y.append(u * math.sin(theta) * t - 0.5 * g * t * t)
    draw_graph(x, y)

if __name__ == '__main__':
    n = 0
    while n == 0:
        try:
            n = int(input('How many trajectories? '))
        except Exception as err:
            print(type(err), err)

    i = 1
    while i <= n:
        try:
            u = float(input(f'Enter the initial velocity {i}(m/s): '))
            theta = float(
                input(f'Enter the angle of projection {i}(degrees): '))
        except ValueError:
            print('You entered an invalid input')
        else:
            draw_trajectory(u, theta)
            i += 1
    plt.savefig('sample3.svg')

入出力結果(Terminal, Jupyter(IPython))

$ ./sample3.py
How many trajectories? a
<class 'ValueError'> invalid literal for int() with base 10: 'a'
How many trajectories? 3
Enter the initial velocity 1(m/s): a
You entered an invalid input
Enter the initial velocity 1(m/s): 45
Enter the angle of projection 1(degrees): 45
Enter the initial velocity 2(m/s): 60
Enter the angle of projection 2(degrees): 45
Enter the initial velocity 3(m/s): 45
Enter the angle of projection 3(degrees): a
You entered an invalid input
Enter the initial velocity 3(m/s): 45
Enter the angle of projection 3(degrees): 90
$

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