离散时间x轴的概念使这一点有点挑战性，因为，例如，在每个单位时间内，风向可能在所有方向上变化，这会使混合色线--甚至是分段色线--看起来相当混乱。
一个替代选项将是在背景中放置表示方向的条带，例如：

下面的代码使用rect和adjustcolor创建透明条带，我还创建了一个名为directs的向量来简化方向类别。

## Identify directions
directs <- setNames(seq(0, 315, by = 45),
                    c("North", "North-east", "East",
                      "South-east", "South", "South-west", 
                      "West", "North-west"))
# Initiate blank plot
plot(df_wind$date_time, df_wind$wind_direction, type = "n",
     bty = "n", xlab = "Time", ylab = "Direction",
     ylim = c(0, 360))
# Plot bands and text
rect(xleft = min(df_wind$date_time), xright = max(df_wind$date_time),
       ybottom = directs, ytop = c(directs[-1], 360),
       col = adjustcolor(1:8, alpha.f = 0.2), border = NA)
text(names(directs), pos = 4,
       x = min(df_wind$date_time), y = directs + 22.5, col = 1:8)
text(names(directs), pos = 2,
       x = max(df_wind$date_time), y = directs + 22.5, col = 1:8)
# Plot lines over bands
lines(df_wind$date_time, df_wind$wind_direction)

另一种选择是绘制点的颜色，而不是线的颜色，如下所示：

为此，我在数据集df_wind$direction中创建了一个新变量：

df_wind <- dplyr::mutate(df_wind, direction = dplyr::case_when(
  wind_direction <= 45 ~ "North",
  wind_direction > 45 & wind_direction <= 90 ~ "North-east",
  wind_direction > 90 & wind_direction <= 135 ~ "East",
  wind_direction > 135 & wind_direction <= 180 ~ "South-east",
  wind_direction > 180 & wind_direction <= 225 ~ "South",
  wind_direction > 225 & wind_direction <= 270 ~ "South-west",
  wind_direction > 270 & wind_direction <= 315 ~ "West",
  wind_direction > 315 ~ "North-west"
))

dirs <- names(directs)
  
plot(df_wind$date_time, df_wind$wind_direction, type = "l",
       bty = "n", xlab = "Time", ylab = "Direction",
       ylim = c(0, 360))
for(i in seq_along(unique(df_wind$direction))){
  points(df_wind$date_time[df_wind$direction == dirs[i]], 
        df_wind$wind_direction[df_wind$direction == dirs[i]], 
        pch = 21, bg = i)
}
legend("topright", dirs, pch = 21, pt.bg = 1:8, bty = "n", ncol = 2)

或者为什么不两者兼顾？

plot(df_wind$date_time, df_wind$wind_direction, type = "l",
       bty = "n", xlab = "Time", ylab = "Direction",
       ylim = c(0, 360))
rect(xleft = min(df_wind$date_time), xright = max(df_wind$date_time),
     ybottom = directs, ytop = c(directs[-1], 360),
     col = adjustcolor(1:8, alpha.f = 0.2), border = NA)
for(i in seq_along(unique(df_wind$direction))){
  points(df_wind$date_time[df_wind$direction == dirs[i]], 
        df_wind$wind_direction[df_wind$direction == dirs[i]], 
        pch = 21, bg = i)
}
legend("topright", dirs, pch = 21, pt.bg = 1:8, bty = "n", ncol = 2)

最后，您可以根据最近的位置对行进行着色（并添加彩色点-要删除它们，只需删除points循环），如您的评论中所述，但您再次可以看到混乱。

plot(df_wind$date_time, df_wind$wind_direction, type = "n",
     bty = "n", xlab = "Time", ylab = "Direction",
     ylim = c(0, 360))
for(i in 1:nrow(df_wind)){
  if(i != nrow(df_wind)){
    lines(df_wind$date_time[i:(i + 1)], df_wind$wind_direction[i:(i + 1)],
          col = grep(df_wind$direction[i+1], names(directs)))
  }
for(i in seq_along(unique(df_wind$direction))){
  points(df_wind$date_time[df_wind$direction == dirs[i]], 
         df_wind$wind_direction[df_wind$direction == dirs[i]], 
         pch = 21, bg = i)
}
}