随心所欲地运用ggplot2画图

1. 画一个黑点

library(tidyverse)

# 构造数据
df = data_frame(x = 0, y = 0)  # 仅有一个点，位于原点位置

# 绘图
ggplot() +
  geom_point(data = df, aes(x, y)) +  # 画点
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +      # 控制图像范围
  theme_void()                        # 去掉坐标轴等内容

2. 调整黑点大小

ggplot() +
  geom_point(data = df, aes(x, y), size = 20) +  # 设置点的大小
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +
  theme_void()

3. 画圆（基于画多边形）

df = data_frame(t = seq(0, 2 * pi, length.out=100)) %>%  # 构造基础序列t
  mutate(x = cos(t),
         y = sin(t))  # 使用标准圆曲线，基于t获得相应x, y坐标

ggplot() +
  geom_polygon(data = df, aes(x, y),
               color = "black",
               fill = "blue") +  # 画多边形（按顺序描出曲线，并填充）
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +
  theme_void()

4. 画椭圆

width = 0.8   # 椭圆宽
height = 0.5  # 椭圆高

df = data_frame(t = seq(0, 2 * pi, length.out=100)) %>%
  mutate(x = cos(t) * width,
         y = sin(t) * height)  # 调整椭圆的宽和高

ggplot() +
  geom_polygon(data = df, aes(x, y),
               color = "black", fill = "red") +
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +
  theme_void()

5. 平移并旋转椭圆

width = 0.8
height = 0.5
dx = 0.3   # 水平平移
dy = -0.1  # 垂直平移
theta = pi / 6   # 旋转角度

df = data_frame(t = seq(0, 2 * pi, length.out=100)) %>%
  mutate(x0 = sin(t) * width,
         y0 = cos(t) * height,  # 先计算原始坐标
         x = dx + x0 * cos(theta) - y0 * sin(theta),
         y = dy + x0 * sin(theta) + y0 * cos(theta))  # 平移并旋转

ggplot() +
  geom_polygon(data = df, aes(x, y),
               color = "black", fill = "green") +
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +
  theme_void()

6. 画扇形

start_angle = pi / 6  # 扇形起始角度
end_angle = pi / 3    # 扇形终止角度

df = data_frame(t = seq(start_angle, end_angle,
                        length.out=100)) %>%  # 调整起始和终止
  mutate(x = sin(t),
         y = cos(t)) %>%
  rbind(data_frame(t = 0, x = 0, y = 0))  # 增加一个原点

ggplot() +
  geom_polygon(data = df, aes(x, y),
               color = "black", fill = "brown") +
  coord_fixed(xlim = c(-1, 1),
              ylim = c(-1, 1)) +
  theme_void()

7. 绘制螺旋渐开线

df = data_frame(t = seq(0, 6 * pi, length.out = 1000)) %>% # 绕三圈
  mutate(x = t * cos(t),
         y = t * sin(t))  # 螺旋渐开线

ggplot() +
  geom_path(data = df, aes(x, y)) +
  coord_fixed() +
  theme_void()

7. 绘制心形图

df = data_frame(t = seq(0, 2*pi, length.out=1000)) %>%
  mutate(x = 16 * sin(t)^3,
         y = 13 * cos(t) - 5 * cos(2*t) - 2 * cos(3*t) - cos(4*t))  # 心形线

ggplot() +
  geom_line(data = df, aes(x, y), color = "red") +
  coord_fixed() +
  theme_void()

8. 环绕圆圈画文字

text = "用ggplot画环绕曲线文字很容易"
n = nchar(text)
chars = strsplit(text, '')[[1]]
theta = seq(0, 2 * pi, length.out = n + 1)[-(n + 1)]  # 为避免首尾文字重叠，这里先
                                                      # 多生成一个数，再去掉最后一个

df = data_frame(t = theta) %>%
  mutate(x = cos(t),
         y = sin(t),
         txt = chars)

ggplot() +
  geom_text(data = df, aes(x, y, label = txt)) +
  coord_fixed() +
  theme_void()

9. 环绕曲线画文字

text = "晋太元中，武陵人捕鱼为业，缘溪行，忘路之远近。忽逢桃花林，夹岸数百步，中无杂树，芳草鲜美，落英缤纷，渔人甚异之。复前行，欲穷其林。林尽水源，便得一山，山有小口，仿佛若有光，便舍船从口入。初极狭，才通人，复行数十步，豁然开朗。土地平旷，屋舍俨然，有良田美池桑竹之属。阡陌交通，鸡犬相闻。其中往来种作，男女衣著，悉如外人。黄发垂髫，并怡然自乐。"
n = nchar(text)
chars = strsplit(text, '')[[1]]
theta = seq(6 * pi, 12 * pi, length.out = n)

df = data_frame(t = theta) %>%
  mutate(x = t * cos(t),
         y = t * sin(t),
         txt = chars)

ggplot() +
  geom_text(data = df, aes(x, y, label = txt)) +
  coord_fixed() +
  theme_void()