r - 如何使用 ggplot 获得真正周期性的极地表面图

Question

示例数据:

mydata="theta,rho,value
0,0.8400000,0.0000000
40,0.8400000,0.4938922
80,0.8400000,0.7581434
120,0.8400000,0.6675656
160,0.8400000,0.2616592
200,0.8400000,-0.2616592
240,0.8400000,-0.6675656
280,0.8400000,-0.7581434
320,0.8400000,-0.4938922
360,0.8400000,0.0000000
0,0.8577778,0.0000000
40,0.8577778,0.5152213
80,0.8577778,0.7908852
120,0.8577778,0.6963957
160,0.8577778,0.2729566
200,0.8577778,-0.2729566
240,0.8577778,-0.6963957
280,0.8577778,-0.7908852
320,0.8577778,-0.5152213
360,0.8577778,0.0000000
0,0.8755556,0.0000000
40,0.8755556,0.5367990
80,0.8755556,0.8240077
120,0.8755556,0.7255612
160,0.8755556,0.2843886
200,0.8755556,-0.2843886
240,0.8755556,-0.7255612
280,0.8755556,-0.8240077
320,0.8755556,-0.5367990
360,0.8755556,0.0000000
0,0.8933333,0.0000000
40,0.8933333,0.5588192
80,0.8933333,0.8578097
120,0.8933333,0.7553246
160,0.8933333,0.2960542
200,0.8933333,-0.2960542
240,0.8933333,-0.7553246
280,0.8933333,-0.8578097
320,0.8933333,-0.5588192
360,0.8933333,0.0000000
0,0.9111111,0.0000000
40,0.9111111,0.5812822
80,0.9111111,0.8922910
120,0.9111111,0.7856862
160,0.9111111,0.3079544
200,0.9111111,-0.3079544
240,0.9111111,-0.7856862
280,0.9111111,-0.8922910
320,0.9111111,-0.5812822
360,0.9111111,0.0000000
0,0.9288889,0.0000000
40,0.9288889,0.6041876
80,0.9288889,0.9274519
120,0.9288889,0.8166465
160,0.9288889,0.3200901
200,0.9288889,-0.3200901
240,0.9288889,-0.8166465
280,0.9288889,-0.9274519
320,0.9288889,-0.6041876
360,0.9288889,0.0000000
0,0.9466667,0.0000000
40,0.9466667,0.6275358
80,0.9466667,0.9632921
120,0.9466667,0.8482046
160,0.9466667,0.3324593
200,0.9466667,-0.3324593
240,0.9466667,-0.8482046
280,0.9466667,-0.9632921
320,0.9466667,-0.6275358
360,0.9466667,0.0000000
0,0.9644444,0.0000000
40,0.9644444,0.6512897
80,0.9644444,0.9997554
120,0.9644444,0.8803115
160,0.9644444,0.3450427
200,0.9644444,-0.3450427
240,0.9644444,-0.8803115
280,0.9644444,-0.9997554
320,0.9644444,-0.6512897
360,0.9644444,0.0000000
0,0.9822222,0.0000000
40,0.9822222,0.6751215
80,0.9822222,1.0363380
120,0.9822222,0.9125230
160,0.9822222,0.3576658
200,0.9822222,-0.3576658
240,0.9822222,-0.9125230
280,0.9822222,-1.0363380
320,0.9822222,-0.6751215
360,0.9822222,0.0000000
0,1.0000000,0.0000000
40,1.0000000,0.6989533
80,1.0000000,1.0729200
120,1.0000000,0.9447346
160,1.0000000,0.3702890
200,1.0000000,-0.3702890
240,1.0000000,-0.9447346
280,1.0000000,-1.0729200
320,1.0000000,-0.6989533
360,1.0000000,0.0000000"

读入一个数据框:

foobar <- read.csv(text = mydata)

您可以检查(如果您真的想要!)数据在 theta 方向上是周期性的，即对于每个给定的 rho， 处的点>theta=0 和 theta=360 完全相同。我想绘制一个漂亮的极地表面图，换句话说，一个根据 value 着色的环面。我尝试了以下方法:

library(viridis) # just because I very much like viridis: if you don't want to install it, just comment this line and uncomment the scale_fill_distiller line
library(ggplot2)
p <- ggplot(data = foobar, aes(x = theta, y = rho, fill = value)) +
geom_tile() + 
coord_polar(theta = "x") +
scale_x_continuous(breaks = seq(0, 360, by = 45), limits=c(0,360)) +
scale_y_continuous(limits = c(0, 1)) +
# scale_fill_distiller(palette = "Oranges")
scale_fill_viridis(option = "plasma")

我得到:

呸!为什么环状物上有讨厌的洞？如果我生成一个包含更多行(更多 theta 和 rho 值)的 foobar 数据框，这个洞就会变小。这不是一个可行的解决方案，因为以更多的 rho/theta 值计算数据既昂贵又耗时，而且即使有 100x100=10^4 行我仍然会遇到漏洞。此外，对于更大的数据帧，ggplot 需要很长时间才能渲染绘图:geom_tile 和 coord_polar 的组合效率极低。有没有办法在不浪费内存和 CPU 时间的情况下获得漂亮的极坐标图？

Answer 1

编辑:删除了 theta=360 的所有 data 值(从 theta=0 的值开始重复)

   ggplot(data = foobar, aes(x = theta, y = rho, fill = value)) +
      geom_tile() + 
      coord_polar(theta = "x",start=-pi/9) +
      scale_y_continuous(limits = c(0, 1))+
      scale_x_continuous(breaks = seq(0, 360, by = 45))

我刚刚从 scale_x_continuous 中删除了 limits这给了我: