文本与标注

Axes.text(
    x, y,               # 文字锚点位置，坐标制由 transform 决定（默认 data）
    s,                  # 文字内容；支持 $...$ mathtext 与 \n 换行
    fontdict=None,      # 字体属性字典（等价于直接写 fontsize= 等 kwargs）
    **kwargs            # 其余 Text 属性：ha/va/fontsize/color/rotation/bbox/transform...
)

Axes.annotate(
    text,                       # 文字内容
    xy,                         # ★ 被指向的点（箭头尖端落在这里）
    xytext=None,                # ★ 文字位置；不给就等于 xy（文字压住箭头尖）
    xycoords="data",            # xy 用的坐标系
    textcoords=None,            # xytext 用的坐标系；默认跟随 xycoords
    arrowprops=None,            # ★ 箭头属性字典；不给就没有箭头
    annotation_clip=None,       # 锚点跑到轴外时还画不画
    **kwargs                    # 其余 Text 属性
)

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots(figsize=(6, 4))
ax.plot(np.arange(10) ** 2)
ax.text(3, 9, '纯数据坐标', fontsize=12)                     # 默认 data：跟着数据缩放
ax.text(.05, .9, 'axes 比例坐标', transform=ax.transAxes)     # 相对子图，0~1
ax.text(.5, -.15, 'figure 图外', transform=fig.transFigure, ha='center')
plt.show()

import numpy as np
import matplotlib.pyplot as plt

plt.rcParams["font.sans-serif"] = ["SimHei", "Microsoft YaHei", "DejaVu Sans"]
plt.rcParams["axes.unicode_minus"] = False

x = np.arange(1, 13)
y = np.array([12, 15, 14, 19, 24, 22, 28, 31, 30, 36, 42, 48])

fig, axes = plt.subplots(1, 3, figsize=(15, 4.6))

for ax in axes:
    ax.plot(x, y, marker="o", ms=4, color="#1f77b4", lw=1.8)
    ax.set_xlabel("月份")
    ax.set_ylabel("销量")

# ---- (a) 三套坐标系各贴一处 ----
axes[0].text(0.03, 0.92, "axes 比例（钉死）", transform=axes[0].transAxes,
             fontsize=9, color="#333333")
axes[0].text(0.03, 0.82, "data 坐标（跟着数据走）", fontsize=9, color="#C44E52")
axes[0].text(0.98, 0.02, "右下角", transform=axes[0].transAxes,
             ha="right", va="bottom", fontsize=9, color="#2b8a3e")
axes[0].set_title("(a) 三种 transform")

# ---- (b) 标注峰值：箭头指数据、文字在空白区 ----
iy = int(np.argmax(y))
axes[1].annotate(f"峰值 {y[iy]}",
                 xy=(x[iy], y[iy]), xycoords="data",
                 xytext=(0.05, 0.85), textcoords="axes fraction",
                 arrowprops=dict(arrowstyle="-|>", color="#C44E52", lw=1.4,
                                 connectionstyle="arc3,rad=0.25",
                                 shrinkA=6, shrinkB=6),
                 fontsize=10, color="#C44E52",
                 bbox=dict(boxstyle="round,pad=0.35", fc="white",
                           ec="#C44E52", alpha=0.9))
axes[1].set_title("(b) 跨坐标系 + 弯箭头 + bbox")

# ---- (c) 框出区间 + 标注在图外 ----
axes[2].axvspan(6.5, 9.5, color="#55A868", alpha=0.12)
axes[2].annotate("旺季", xy=(8, 0), xycoords=("data", "axes fraction"),
                 xytext=(0.62, -0.22), textcoords="axes fraction",
                 ha="center", va="top", fontsize=10, color="#2b8a3e",
                 arrowprops=dict(arrowstyle="->", color="#2b8a3e", lw=1.2),
                 annotation_clip=False)
axes[2].set_title("(c) 标注放到轴外（clip=False）")

plt.tight_layout()
plt.show()

Text(x, y, s,
     bbox=dict(
         boxstyle="round,pad=0.3",   # ★ 形状 + 形状参数，全在这一个字符串里
         fc="white", ec="red",       # Patch 属性：底色 / 边色（facecolor / edgecolor 同义）
         lw=1.0,                     # 边宽
         alpha=None,                 # 整体透明度
         mutation_aspect=1,          # 垂直方向形变倍数
         mutation_scale=1,           # 形状整体放大倍数
     ))

Artist.set_path_effects([
    pe.Stroke(linewidth=8, foreground="gold"),   # 第一层：粗金色描边
    pe.Normal(),                                 # ★ 最后一层：原色本体，漏了就没了
])

import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [1, 4, 2])

ax.text(2, 4, 'round,pad=0.3', ha='center', va='bottom',
        bbox=dict(boxstyle='round,pad=0.3', fc='#fff3bf', ec='#f08c00'))
ax.text(3, 2, 'square', ha='left', va='center',
        bbox=dict(boxstyle='square,pad=0.4', fc='#e7f5ff', ec='#1971c2'))
plt.show()

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.set_xlim(0, 6); ax.set_ylim(0, 3); ax.axis('off')
for i, st in enumerate(['round', 'larrow', 'roundtooth', 'circle']):
    ax.text(0.7 + i * 1.4, 1.6, st, ha='center', va='center', fontsize=8,
            bbox=dict(boxstyle=f'{st},pad=0.45', fc='#e7f5ff', ec='#1971c2'))
plt.show()

import inspect
from matplotlib.patches import BoxStyle

for name in sorted(BoxStyle._style_list):
    print(name, inspect.signature(BoxStyle._style_list[name].__init__))
# 输出: circle (self, pad=0.3)
# 输出: darrow (self, pad=0.3)
# 输出: ellipse (self, pad=0.3)
# 输出: larrow (self, pad=0.3)
# 输出: rarrow (self, pad=0.3)
# 输出: round (self, pad=0.3, rounding_size=None)
# 输出: round4 (self, pad=0.3, rounding_size=None)
# 输出: roundtooth (self, pad=0.3, tooth_size=None)
# 输出: sawtooth (self, pad=0.3, tooth_size=None)
# 输出: square (self, pad=0.3)

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.patheffects as pe

fig, axes = plt.subplots(1, 3, figsize=(13, 3.6))
x = np.linspace(0, 10, 200)

# ① 三种底片风格
ax = axes[0]
ax.plot(x, np.sin(x), color='0.6', lw=1)
ax.text(1.2, .55, '结论 A', bbox=dict(boxstyle='round,pad=0.35', fc='#fff3bf', ec='#f08c00'))
ax.text(3.0, .05, '结论 B', bbox=dict(boxstyle='larrow,pad=0.35', fc='#e7f5ff', ec='#1971c2'))
ax.text(5.4, -.55, '结论 C', bbox=dict(boxstyle='circle,pad=0.45', fc='#f8f0fc', ec='#9c36b5'))
ax.set_title('三种 boxstyle', fontsize=9)

# ② 白字红描边压在密集曲线上
ax = axes[1]
for i in range(6):
    ax.plot(x, np.sin(x + i * .4), color=f'C{i}', lw=1.6)
ax.text(5, 0, '峰值区', fontsize=20, color='white', ha='center', va='center',
        path_effects=[pe.withStroke(linewidth=4, foreground='#c92a2a')])
ax.set_title('withStroke：白字压在杂线里也读得清', fontsize=9)

# ③ 线本身加描边 + 阴影
ax = axes[2]
ax.plot(x, np.cos(x), color='#4C72B0', lw=3,
        path_effects=[pe.SimpleLineShadow(offset=(4, -4), alpha=.3),
                      pe.Stroke(linewidth=8, foreground='#f08c00'),
                      pe.Normal()])
ax.set_title('阴影 + 描边 + 本体（三层）', fontsize=9)

plt.tight_layout()
plt.show()