在R或Matlab中绘制一个像这样着色的多边形
我的示例代码如下所示,我不知道如何使用色调颜色着色在R或Matlab中绘制一个像这样着色的多边形,r,matlab,plot,graphics,polygons,R,Matlab,Plot,Graphics,Polygons,我的示例代码如下所示,我不知道如何使用色调颜色着色 plot.koch <- function(k,col="blue"){ plot(0,0,xlim=c(0,1), ylim=c(-sqrt(3)/6,sqrt(3)/2), asp = 1,type="n",xlab="", ylab="") plotkoch <- function(x1,y1,x2,y2,n){ if (n > 1){ plotkoch(x1,y1,(2*x1+x2)/3,
plot.koch <- function(k,col="blue"){
plot(0,0,xlim=c(0,1), ylim=c(-sqrt(3)/6,sqrt(3)/2), asp = 1,type="n",xlab="", ylab="")
plotkoch <- function(x1,y1,x2,y2,n){
if (n > 1){
plotkoch(x1,y1,(2*x1+x2)/3,(2*y1+y2)/3,n-1);
plotkoch((2*x1+x2)/3,(2*y1+y2)/3,(x1+x2)/2-(y1-y2)*sqrt(3)/6,(y1+y2)/2-(x2-x1) *sqrt(3)/6,n-1);
plotkoch((x1+x2)/2-(y1-y2)*sqrt(3)/6,(y1+y2)/2-(x2-x1)*sqrt(3)/6,(2*x2+x1)/3,(2 *y2+y1)/3,n-1);
plotkoch((2*x2+x1)/3,(2*y2+y1)/3,x2,y2,n-1)
}
else {
x=c(x1,(2*x1+x2)/3,(x1+x2)/2-(y1-y2)*sqrt(3)/6,(2*x2+x1)/3,x2);
y=c(y1,(2*y1+y2)/3,(y1+y2)/2-(x2-x1)*sqrt(3)/6,(2*y2+y1)/3,y2);
polygon(x,y,type="l",col=col)
}
}
plotkoch(0,0,1,0,k)
plotkoch(0.5,sqrt(3)/2,0,0,k)
plotkoch(1,0,0.5,sqrt(3)/2,k)
}
plot.koch(3, col=3)
plot.koch我会这样做:
对于任何绘制像素,获取其位置x,y
计算角度=atan2(y-y0,x-x0)
其中x0,y0
是科赫的雪花中间位置
根据角度计算颜色
如果您使用HSV,则hue=angle
并计算目标颜色值(我假设RGB)。如果您想要可见光谱颜色,可以试试我的:
只需将角度范围angle=[rad]
转换为波长l=[nm]
l = 400.0 + (700.0-400.0)*angle/(2.0*M_PI)
渲染像素
[Notes]
不使用R或Matlab,因此需要自己编写代码。角度可能需要一些移动来匹配坐标系,例如:
const angle0=???; // some shift constant [rad]
angle+=angle0; // or angle=angle0-angle; if the direction is oposite
if (angle>=2.0*M_PI) angle-=2.0*M_PI;
if (angle< 0.0) angle+=2.0*M_PI;
const angle0=???;//某些移位常数[rad]
角度+=角度0;//或角度=角度0角度;如果方向是oposite
如果(角度>=2.0*M_-PI)角度-=2.0*M_-PI;
如果(角度<0.0)角度+=2.0*M_π;
如果将其绘制为多边形,则需要计算每个顶点的颜色,而不是每个像素的颜色,但这样会出现问题,因为这不是凸多边形。那么如何保证中点颜色???我担心你将需要使用一些三角测量,因为简单的三角形风扇将失败
唯一显而易见的是填充整个空间的颜色,然后用黑色绘制轮廓,然后用白色从外部泛光填充所有非黑色像素。目前,它还绘制雪花外部的颜色。如果您能够确定点是在雪花内部还是外部,那么您应该能够在df_fill
中删除外部点。
这里我首先创建用于绘制多边形的data.frame
。然后我为背景色创建data.frame
。最后,我使用ggplot2
来绘制数据
# creating relevant data
data.koch <- function(k){
df <- data.frame(x = 0,
y = 0,
grp = 0)
plotkoch <- function(x1, y1, x2, y2, n, data){
if (n==1) {
x=c(x1,(2*x1+x2)/3,(x1+x2)/2-(y1-y2)*sqrt(3)/6,(2*x2+x1)/3,x2)
y=c(y1,(2*y1+y2)/3,(y1+y2)/2-(x2-x1)*sqrt(3)/6,(2*y2+y1)/3,y2)
df <- rbind(data, data.frame(x, y, grp=max(data$grp)+1))
}
if (n > 1){
df <- plotkoch(x1,y1,(2*x1+x2)/3,(2*y1+y2)/3,n-1, data = data)
df <- plotkoch((2*x1+x2)/3,(2*y1+y2)/3,(x1+x2)/2-(y1-y2)*sqrt(3)/6,(y1+y2)/2-(x2-x1) *sqrt(3)/6,n-1, data=df)
df <- plotkoch((x1+x2)/2-(y1-y2)*sqrt(3)/6,(y1+y2)/2-(x2-x1)*sqrt(3)/6,(2*x2+x1)/3,(2 *y2+y1)/3,n-1, data=df)
df <- plotkoch((2*x2+x1)/3,(2*y2+y1)/3,x2,y2,n-1, data=df)
}
return(df)
}
df <- plotkoch(0,0,1,0,k, data = df)
df <- plotkoch(0.5,sqrt(3)/2,0,0,k, data = df)
df <- plotkoch(1,0,0.5,sqrt(3)/2,k, data = df)
return(df)
}
# plotting functon
plot.koch <- function(k){
stopifnot(require(ggplot2))
if (is.data.frame(k)) df <- k
else df <- data.koch(k)
# filling data (CHANGE HERE TO GET ONLY INSIDE POINTS)
l <- 500
df_fill <- expand.grid(x=seq(0, 1, length=l),
y=seq(-sqrt(3)/6, sqrt(3)/2, length=l))
df_fill[, "z"] <- atan2(-df_fill[, "y"] + sqrt(3)/6, df_fill[, "x"] - 0.5) + pi/2
df_fill[df_fill[, "z"] < 0, "z"] <- df_fill[df_fill[, "z"] < 0, "z"] + 2*pi
# plotting
ggplot(df, aes(x, y, group=grp)) +
geom_raster(data = df_fill,
aes(fill=z, group=NULL),
hjust = 0,
vjust = 0,
linetype='blank') +
geom_path(data=df, size=1) +
scale_fill_gradientn(colours = rainbow(30), guide = 'none') +
scale_x_continuous(name = '', limits = c(0, 1), expand=c(0, 0)) +
scale_y_continuous(name = '', limits = c(-sqrt(3)/6,sqrt(3)/2), expand=c(0, 0)) +
coord_fixed() +
theme_bw() +
theme(axis.line = element_blank(),
panel.grid = element_blank(),
axis.ticks = element_blank(),
axis.text = element_blank())
}
#
p <- plot.koch(4)
print(p)
#创建相关数据
data.koch这里有一种方法使用R中的空间对象,混合使用sp
、rgeos
和光栅
包
对函数进行轻微修改,以将x
,y
坐标返回给用户(并按正确顺序):
加载空间包,从fractal创建空间多边形
对象,并绘制一次以设置绘图区域
library(sp)
library(rgeos)
library(raster)
poly <- SpatialPolygons(list(Polygons(list(Polygon(xy)), 1)))
plot(poly)
再次绘制多边形
plot(poly, add=TRUE)
这是我的网格解决方案
##data
koch <- function(k) {
yy <- xx <- numeric(0)
Koch <- function(x1, y1, x2, y2, n) {
if (n > 1) {
Koch(x1, y1, (2 * x1 + x2)/3, (2 * y1 + y2)/3, n - 1)
Koch((2 * x1 + x2)/3, (2 * y1 + y2)/3, (x1 + x2)/2 - (y1 -
y2) * sqrt(3)/6, (y1 + y2)/2 - (x2 - x1) * sqrt(3)/6,
n - 1)
Koch((x1 + x2)/2 - (y1 - y2) * sqrt(3)/6, (y1 + y2)/2 -
(x2 - x1) * sqrt(3)/6, (2 * x2 + x1)/3, (2 * y2 + y1)/3,
n - 1)
Koch((2 * x2 + x1)/3, (2 * y2 + y1)/3, x2, y2, n - 1)
} else {
x <- c(x1, (2 * x1 + x2)/3, (x1 + x2)/2 - (y1 - y2) * sqrt(3)/6,
(2 * x2 + x1)/3, x2)
xx <<- c(xx, x)
y <- c(y1, (2 * y1 + y2)/3, (y1 + y2)/2 - (x2 - x1) * sqrt(3)/6,
(2 * y2 + y1)/3, y2)
yy <<- c(yy, y)
}
}
Koch(0, 0, 1, 0, k)
Koch(1, 0, 0.5, sqrt(3)/2, k)
Koch(0.5, sqrt(3)/2, 0, 0, k)
xy <- data.frame(x = (xx - min(xx))/(max(xx) - min(xx)), y = (yy -
min(yy))/(max(yy) - min(yy)))
rbind(unique(xy), xy[1, ])
}
xy <- koch(5)
##Plot
library(grid)
grid.newpage()
pushViewport(dataViewport(xy$x, xy$y), plotViewport(c(1, 1, 1, 1)))
for (i in 1:nrow(xy)) {
grid.path(x = c(xy[i, 1], xy[i + 1, 1], mean(xy$x)),
y = c(xy[i, 2], xy[i + 1, 2], mean(xy$y)),
gp = gpar(col = rainbow(nrow(xy))[i],
fill = rainbow(nrow(xy))[i]))
}
##数据
科赫
library(sp)
library(rgeos)
library(raster)
poly <- SpatialPolygons(list(Polygons(list(Polygon(xy)), 1)))
plot(poly)
r <- 1
mapply(function(theta, col) {
segments(0.5, 0.3, 0.5 + r*cos(theta), 0.3 + r*sin(theta), lwd=3, col=col)
}, seq(0, 360, length=1000)*pi/180, colr(1000))
plot(gDifference(as(extent(par('usr')), 'SpatialPolygons'), poly),
col='white', border='white', add=TRUE)
plot(poly, add=TRUE)
##data
koch <- function(k) {
yy <- xx <- numeric(0)
Koch <- function(x1, y1, x2, y2, n) {
if (n > 1) {
Koch(x1, y1, (2 * x1 + x2)/3, (2 * y1 + y2)/3, n - 1)
Koch((2 * x1 + x2)/3, (2 * y1 + y2)/3, (x1 + x2)/2 - (y1 -
y2) * sqrt(3)/6, (y1 + y2)/2 - (x2 - x1) * sqrt(3)/6,
n - 1)
Koch((x1 + x2)/2 - (y1 - y2) * sqrt(3)/6, (y1 + y2)/2 -
(x2 - x1) * sqrt(3)/6, (2 * x2 + x1)/3, (2 * y2 + y1)/3,
n - 1)
Koch((2 * x2 + x1)/3, (2 * y2 + y1)/3, x2, y2, n - 1)
} else {
x <- c(x1, (2 * x1 + x2)/3, (x1 + x2)/2 - (y1 - y2) * sqrt(3)/6,
(2 * x2 + x1)/3, x2)
xx <<- c(xx, x)
y <- c(y1, (2 * y1 + y2)/3, (y1 + y2)/2 - (x2 - x1) * sqrt(3)/6,
(2 * y2 + y1)/3, y2)
yy <<- c(yy, y)
}
}
Koch(0, 0, 1, 0, k)
Koch(1, 0, 0.5, sqrt(3)/2, k)
Koch(0.5, sqrt(3)/2, 0, 0, k)
xy <- data.frame(x = (xx - min(xx))/(max(xx) - min(xx)), y = (yy -
min(yy))/(max(yy) - min(yy)))
rbind(unique(xy), xy[1, ])
}
xy <- koch(5)
##Plot
library(grid)
grid.newpage()
pushViewport(dataViewport(xy$x, xy$y), plotViewport(c(1, 1, 1, 1)))
for (i in 1:nrow(xy)) {
grid.path(x = c(xy[i, 1], xy[i + 1, 1], mean(xy$x)),
y = c(xy[i, 2], xy[i + 1, 2], mean(xy$y)),
gp = gpar(col = rainbow(nrow(xy))[i],
fill = rainbow(nrow(xy))[i]))
}