R 从极坐标变换角度

我需要一些天使方面的帮助

使用软件包

fossil

和函数

fossil:：earth.bear

计算轴承，根据帮助

“地球仪上任意两点之间从正北顺时针方向以度为单位的轴承”

我有一个用这个函数得到的角度向量，我需要对它们进行变换，使原点（0º）在x轴（东）上，角度逆时针递增

基本上，我需要一种方法顺时针旋转90º角度（因此0º将位于x轴“朝东”），然后以相反方向（逆时针）计算角度

直观地说，我试着给我的轴承加上90º（顺时针旋转），然后从360度中减去它们（计算“相反方向”的角度）

然而，它不起作用，我高度怀疑每个象限有不同的事情要做，但我就是想不出来

下面用虚拟数据和极坐标直方图进行测试，以证明解决方案不起作用，因为结果向量

轴承2

不等同于起始向量

轴承

# Generate vector with 100 random values between 0 and 360
set.seed(123)
bearing <- runif(100, 0,360)
# generate a histogram with values binned every 5º
breaks = seq(0, 360, by=5)   
bearing.cut = cut(bearing, breaks, right=FALSE) 
bearing.freq = as.data.frame(table(bearing.cut))
bearing.freq$bearing.cut <- seq(5,360, by = 5)
#plot with ggplot
library(ggplot2)
ggplot(bearing.freq, aes(x = bearing.cut, y = Freq)) +
  coord_polar(theta = "x", start = 0 direction = 1) + #start 0 for north, direction 1 for cloclwise
  geom_bar(stat = "identity") +
  scale_x_continuous(breaks = seq(0, 360, 5))

#生成100个介于0和360之间的随机值的向量
种子集（123）
轴承好的，我想我已经弄明白了，但不确定它为什么会起作用。我就把它留在这里，把问题标记为已回答

解决方案是，对于第一个象限（0º和90º之间的角度，我们需要计算角度，因此我们需要
90方位
。对于其余象限，我们按照Gregor的建议（
360-（方位-90）
）

下面是一个可复制的示例的完整代码

library(ggplot2)
set.seed(123)

# 0º at North and clockwise
bearing <- runif(100, 0,360)

#create histogram
breaks = seq(0, 360, by=5)    # half-integer sequence 
bearing.cut = cut(bearing, breaks, right=FALSE) 
bearing.freq = as.data.frame(table(bearing.cut))
bearing.freq$bearing.cut <- seq(5,360, by = 5)

#plot
p1 <- ggplot(bearing.freq, aes(x = bearing.cut, y = Freq)) +
        coord_polar(theta = "x", start =0, direction = 1) +
        geom_bar(stat = "identity") +
        scale_x_continuous(breaks = seq(0, 360, 5))

# transform to 0º at E and counterclockwise
bearing2 <- ifelse(bearing <=90, (90-bearing), (360 - (bearing - 90)))

#create histogram
bearing.cut2 = cut(bearing2, breaks, right=FALSE) 
bearing.freq2 = as.data.frame(table(bearing.cut2))
bearing.freq2$bearing.cut <- seq(5,360, by = 5)

# plot
p2 <- ggplot(bearing.freq2, aes(x = bearing.cut, y = Freq)) +
        coord_polar(theta = "x", start = -pi/2, direction = -1) +
        geom_bar(stat = "identity") +
        scale_x_continuous(breaks = seq(0, 360, 5))

require(gridExtra)
grid.arrange(p1, p2, ncol=2)

库（ggplot2）
种子集（123）
#以北顺时针方向0º
轴承尚未完全读取，但您会说“我已尝试向轴承添加90º（顺时针旋转）”。通常添加角度是逆时针旋转。请尝试
360-（轴承-90）
。
library(ggplot2)
set.seed(123)

# 0º at North and clockwise
bearing <- runif(100, 0,360)

#create histogram
breaks = seq(0, 360, by=5)    # half-integer sequence 
bearing.cut = cut(bearing, breaks, right=FALSE) 
bearing.freq = as.data.frame(table(bearing.cut))
bearing.freq$bearing.cut <- seq(5,360, by = 5)

#plot
p1 <- ggplot(bearing.freq, aes(x = bearing.cut, y = Freq)) +
        coord_polar(theta = "x", start =0, direction = 1) +
        geom_bar(stat = "identity") +
        scale_x_continuous(breaks = seq(0, 360, 5))

# transform to 0º at E and counterclockwise
bearing2 <- ifelse(bearing <=90, (90-bearing), (360 - (bearing - 90)))

#create histogram
bearing.cut2 = cut(bearing2, breaks, right=FALSE) 
bearing.freq2 = as.data.frame(table(bearing.cut2))
bearing.freq2$bearing.cut <- seq(5,360, by = 5)

# plot
p2 <- ggplot(bearing.freq2, aes(x = bearing.cut, y = Freq)) +
        coord_polar(theta = "x", start = -pi/2, direction = -1) +
        geom_bar(stat = "identity") +
        scale_x_continuous(breaks = seq(0, 360, 5))

require(gridExtra)
grid.arrange(p1, p2, ncol=2)