如何消除R语言折线图X、Y轴上的加粗线段？

问题原因 #

使用xaxs="i"和yaxs="i"时，绘图区域边界与数据极值完全对齐，刻度线端点和轴线重叠，在Posit Cloud渲染环境下产生视觉上的加粗效果。

解决方案 #

以下几种方法可解决问题，同时保留紧凑的绘图区域（无需将轴起点设为0）：

方法1：统一轴线与刻度线线宽

在plot函数中直接指定axis.lwd参数，确保轴线和刻度线使用相同线宽，避免重叠加粗：

plot(
  x= 1:13, 
  y= 3:15,
  xaxs = "i", 
  yaxs = "i",
  type="l", 
  col="#32a852", 
  bty = "l",
  xlab = 'Bias Current [mA]', 
  ylab = "Voltage [V]", 
  main ="IV Characteristic of 1270nm Laser",
  axis.lwd = 1  # 统一线宽为1（可根据需求调整）
)

方法2：调整刻度线方向

将刻度线改为向内绘制，避免与轴线重叠：

# 临时设置刻度线向内
par(tcl = 0.5)
plot(
  x= 1:13, 
  y= 3:15,
  xaxs = "i", 
  yaxs = "i",
  type="l", 
  col="#32a852", 
  bty = "l",
  xlab = 'Bias Current [mA]', 
  ylab = "Voltage [V]", 
  main ="IV Characteristic of 1270nm Laser"
)
# 恢复默认刻度线方向（向外）
par(tcl = -0.5)

方法3：手动绘制边框与轴

关闭默认边框，手动绘制统一线宽的L型边框和轴：

plot(
  x= 1:13, 
  y= 3:15,
  xaxs = "i", 
  yaxs = "i",
  type="l", 
  col="#32a852", 
  bty = "n",  # 不绘制默认边框
  xlab = 'Bias Current [mA]', 
  ylab = "Voltage [V]", 
  main ="IV Characteristic of 1270nm Laser"
)
# 绘制L型边框
box(bty = "l", lwd = 1)
# 添加X、Y轴
axis(1, lwd = 1)
axis(2, lwd = 1)

内容的提问来源于stack exchange，提问作者Haydn C