如何用R的ggplot2绘制正弦函数并定位到x轴指定坐标处

实现方法 #

方法1：无需修改原有数据框，直接调整偏移量 #

你当前的x_1是取值范围为[-1, 1]的正弦波动值，默认以0为水平中心，要让四条曲线分别以x=1、x=2、x=3、x=4为中心，直接修改geom_path里x轴映射的偏移值即可：

library(ggplot2)
library(tibble)
df <- data.frame(x = 0:10, y = 0:10)
curve <- tibble( z_1 = seq(0, 20, length.out = 1500),x_1 = sin(z_1),
                z_2 = sin(x_1)+2, z_3 = sin(x_1)+5)

base <- ggplot(df, aes(x, y)) + geom_blank()
base + geom_path(data = curve, aes(x = x_1 + 1,y = z_1), color  ='red')+
  geom_path(data = curve, aes(x = x_1 + 2,y = z_1), color  ='red')+
  geom_path(data = curve, aes(x = x_1 + 3,y = z_1), color  ='red')+
  geom_path(data = curve, aes(x = x_1 + 4,y = z_1), color  ='red')

方法2：重构数据框为长格式，代码更简洁易维护 #

如果后续要调整曲线数量、样式，推荐把数据重构为长格式，不需要重复写多次geom_path：

library(ggplot2)
library(tibble)
library(tidyr)
library(dplyr)

df <- data.frame(x = 0:10, y = 0:10)
curve <- tibble( z_1 = seq(0, 20, length.out = 1500),x_1 = sin(z_1))

# 生成四个中心坐标，和原数据交叉连接
curve_long <- curve %>%
  crossing(center_x = c(1,2,3,4)) %>%
  mutate(x_final = x_1 + center_x)

ggplot(df, aes(x, y)) + 
  geom_blank() +
  # 按center_x分组，一次性绘制四条曲线
  geom_path(data = curve_long, aes(x = x_final, y = z_1, group = center_x), color = 'red')

内容的提问来源于stack exchange，提问作者Laura