128 lines
3.5 KiB
Python
128 lines
3.5 KiB
Python
# 实际演示：查看字符的编码值
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# 英文例子
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text_en = "Hello"
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print("=" * 50)
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print("英文文本的字符编码")
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print("=" * 50)
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print(f"文本: {text_en}")
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print(f"每个字符的ASCII码: {[ord(c) for c in text_en]}")
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print()
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# 逐个显示
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for c in text_en:
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print(f" '{c}' -> {ord(c)}")
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print()
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print("=" * 50)
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print("中文文本的字符编码")
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print("=" * 50)
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# 中文例子
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text_cn = "你好"
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print(f"文本: {text_cn}")
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print(f"每个字符的UTF-8编码值: {[ord(c) for c in text_cn]}")
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print()
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# 逐个显示
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for c in text_cn:
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print(f" '{c}' -> {ord(c)}")
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# 用chr()函数反向验证：数字编码转字符
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print("验证：数字编码转字符")
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print()
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# 65是大写字母A
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print(f"chr(65) = '{chr(65)}' # 应该是大写字母 A")
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# 97是小写字母a
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print(f"chr(97) = '{chr(97)}' # 应该是小写字母 a")
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# 20013是中文"中"
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print(f"chr(20013) = '{chr(20013)}' # 应该是中文'中'")
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# 25991是中文"文"
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print(f"chr(25991) = '{chr(25991)}' # 应该是中文'文'")
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print("=" * 50)
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print("练习题1答案")
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print("=" * 50)
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# 1. 用 ord() 函数打印 "Hello" 每个字符的ASCII码
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print("1. 'Hello' 的ASCII码:")
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print([ord(c) for c in "Hello"])
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# 2. 验证字符65对应大写字母A
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print()
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print("2. 验证 chr(65):")
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print(f"chr(65) = '{chr(65)}'")
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# 验证范围
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print()
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print("验证 A-Z 的ASCII码范围 (65-90):")
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print([chr(i) for i in range(65, 91)])
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import numpy as np
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print("=" * 50)
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print("NumPy向量创建演示")
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print("=" * 50)
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# 一维向量（只有1个数字）
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v1 = np.array([3])
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print(f"一维向量 v1 = {v1}")
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print(f"v1 有 {len(v1)} 个元素")
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# 二维向量（2个数字，表示平面上的一个点）
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v2 = np.array([2, 3])
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print(f"\n二维向量 v2 = {v2}")
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print(f"v2 有 {len(v2)} 个元素")
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# 三维向量（3个数字，表示立体空间的一个点）
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v3 = np.array([1, 2, 3])
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print(f"\n三维向量 v3 = {v3}")
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print(f"v3 有 {len(v3)} 个元素")
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# 高维向量（机器学习中常用，几十维到几千维）
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v10 = np.array([0.1, 0.5, -0.3, 0.8, 0.2, -0.1, 0.7, 0.3, -0.2, 0.6])
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print(f"\n10维向量 v10 = {v10}")
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print(f"v10 有 {len(v10)} 个元素")
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import numpy as np
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import matplotlib.pyplot as plt
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# 设置中文字体（如果系统有的话）
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try:
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plt.rcParams['font.sans-serif'] = ['SimHei', 'Noto Sans CJK SC', 'WenQuanYi Micro Hei']
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plt.rcParams['axes.unicode_minus'] = False
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except:
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pass # 如果没有中文字体就用默认
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# 创建画布
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fig, ax = plt.subplots(figsize=(8, 8))
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# 定义向量
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vectors = {
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'A = [2, 3]': np.array([2, 3]),
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'B = [4, 1]': np.array([4, 1]),
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'C = [1, 1]': np.array([1, 1]),
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}
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# 画每个向量
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colors = ['red', 'blue', 'green']
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for (name, vec), color in zip(vectors.items(), colors):
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ax.annotate('', xy=vec, xytext=(0, 0),
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arrowprops=dict(arrowstyle='->', color=color, lw=2))
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ax.text(vec[0]+0.1, vec[1]+0.1, name, fontsize=12, color=color)
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# 画坐标系
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ax.axhline(y=0, color='black', linewidth=0.5)
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ax.axvline(x=0, color='black', linewidth=0.5)
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# 设置范围
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ax.set_xlim(-0.5, 5.5)
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ax.set_ylim(-0.5, 4)
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ax.set_xlabel('x (abscissa)', fontsize=12)
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ax.set_ylabel('y (ordinate)', fontsize=12)
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ax.set_title('2D Vector Visualization', fontsize=14)
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ax.grid(True, alpha=0.3)
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ax.set_aspect('equal')
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plt.show()
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print("Note: Arrows represent vectors. Endpoint of arrow = vector endpoint") |