PROSAGA码农传奇-模型可视化-geom_path（）拒绝在coord

<div class =“post-text”itemprop =“text”>
  
    绕过交叉问题可能更为直接：在360/0点进行插值，并将每次旋转绘制为自己的部分。以下是它的工作原理：
  
   <pre>
 <code>
 library(dplyr)
library(ggplot2)

# sample data
n <- 100
df <- data.frame(
 angle.from.ref = seq(0, 800, length.out = n),
 time.step = seq(Sys.time(), by = "min", length.out = n)
)

df %>%
  interpolate.revolutions() %>%
  ggplot(aes(x = angle.from.ref, y = time.step, 
             group = revolution)) +
  geom_line(aes(color = factor(revolution)), size = 1) + # color added for illustration
  scale_x_continuous(limits = c(0, 360),
                     breaks = seq(0, 360, 45)) +
  coord_polar()

</code>
 </pre>
  
    <a href="https://i.stack.imgur.com/Ori7s.png" rel="nofollow noreferrer">
      <img src =“https://i.stack.imgur.com/Ori7s.png”alt =“plot”/>
    </A>
  
  
    代码
     <code>
 interpolate.revolutions
 </code>
     功能：
  
   <pre>
 <code>
 interpolate.revolutions <- function(df, threshold = 360){
 # where df is a data frame with angle in the first column & radius in the second

res <- df

# add a label variable such that each span of 360 degrees belongs to
 # a different revolution
 res$revolution <- res[[1]] %/% threshold

# keep only the angle values within [0, 360 degrees]
 res[[1]] <- res[[1]] %% threshold

# if there are multiple revolutions (i.e. the path needs to cross the 360/0 threshold), 
 # calculate interpolated values & add them to the data frame
 if(n_distinct(res$revolution) > 1){ 
 split.res <- split(res, res$revolution)
 res <- split.res[[1]]
 for(i in seq_along(split.res)[-1]){
 interp.res <- rbind(res[res[[2]] == max(res[[2]]), ],
 split.res[[i]][split.res[[i]][[2]] == min(split.res[[i]][[2]]), ])
 interp.res[[2]] <- interp.res[[2]][[1]] + 
 (threshold - interp.res[[1]][1]) / 
 (threshold - interp.res[[1]][1] + interp.res[[1]][2]) *
 diff(interp.res[[2]])
 interp.res[[1]] <- c(threshold, 0) 
 res <- rbind(res, interp.res, split.res[[i]])
 }
 }
 return(res)
}

</code>
 </pre>
  
    该方法也可以应用于图中的多个线。只需将功能分别应用于每一行：
  
   <pre>
 <code>
 # sample data for two lines, for different angle values taken at different time points
df2 <- data.frame(
 angle.from.ref = c(seq(0, 800, length.out = 0.75 * n),
 seq(0, 1500, length.out = 0.25 * n)),
 time.step = c(seq(Sys.time(), by = "min", length.out = 0.75 * n),
 seq(Sys.time(), by = "min", length.out = 0.25 * n)),
 line = c(rep(1, 0.75*n), rep(2, 0.25*n))
)

df2 %>%
  tidyr::nest(-line) %>%
  mutate(data = purrr::map(data, interpolate.revolutions)) %>%
  tidyr::unnest() %>%

ggplot(aes(x = angle.from.ref, y = time.step, 
             group = interaction(line, revolution),
             color = factor(line))) +
  geom_line(size = 1) +
  scale_x_continuous(limits = c(0, 360),
                     breaks = seq(0, 360, 45)) +
  coord_polar()

</code>
 </pre>
  
    <a href="https://i.stack.imgur.com/n7uwx.png" rel="nofollow noreferrer">
      <img src =“https://i.stack.imgur.com/n7uwx.png”alt =“plot”/>
    </A>
  
</DIV>

geom_path（）拒绝在coord_polar（）中越过0/360行