此代码的目标是在给定的圆方程上找到给定点的象限。 我有两个单独的data.table。在表A中，我有不同的圆方程变量。在表B中，我有原始数据用于查找每个圆象限上有多少个点。我有以下顺序：
我做了一些尝试，但是返回结果有点慢。表格如下：
set.seed(4)
TableA <- data.table(speed=rep(42:44,each=3),
minX = rep(c(1:12),3),
maxX = rep(c(10:21),3),
minY = 1,
maxY = 10,
r = 5,
cX = rep(c(6:17),3),
cY = 6,
indx = 1:36)
TableA
speed minX maxX minY maxY r cX cY indx
1: 42 1 10 1 10 1 2 2 1
2: 42 2 11 1 10 1 2 2 2
3: 42 3 12 1 10 1 2 2 3
4: 43 1 10 1 10 1 2 2 4
5: 43 2 11 1 10 1 2 2 5
6: 43 3 12 1 10 1 2 2 6
7: 44 1 10 1 10 1 2 2 7
8: 44 2 11 1 10 1 2 2 8
9: 44 3 12 1 10 1 2 2 9
TableB <- data.table(speed=rep(42:44,each=100),
x = rep(sample(12),100),
y = rep(sample(12),100),
n = rep(sample(12),100))
TableB
speed x y n
1: 42 8 2 8
2: 42 1 11 10
3: 42 3 5 5
4: 42 10 10 12
5: 42 7 8 11
查找象限的功能：
getQuadrant <- function(X=0,Y=0,R=1,PX=10,PY=10){
#' X and Y are center of the circle
#' R = Radius
#' PX and PY are a point anywhere
# The point is on the center
if (PX == X & PY == Y)
return(0)
val = ((PX - X)^2 + (PY - Y)^2)
# Outside the circle
if (val > R^2)
return(5)
# 1st quadrant
if (PX > X & PY >= Y)
return(1)
# 2nd quadrant
if (PX <= X & PY > Y)
return(2)
# 3rd quadrant
if (PX < X & PY <= Y)
return(3)
# 4th quadrant
if (PX >= X & PY < Y)
return(4)
}
用于返回象限中点数的函数。
Quadrants <- function(dt,radius,centerX,centerY){
#' dt is filtered data for the circle
#' radius of the circle equation
#' centerX and centerY are the center point of the circle equation
if(nrow(dt) > 0 ){
dt[,quadrant:=factor(mapply(function(X,Y,R,PX,PY) getQuadrant(X=X,Y=Y,R=R,PX=PX,PY=PY),centerX,centerY,radius,x_cut,y_cut), levels = c("1","2","3","4","5"))]
dt <- dt[, .(.N), keyby = .(quadrant)]
setkeyv(dt, c("quadrant"))
dt <- dt[CJ(levels(dt[,quadrant])),]
dd <- list(Q1=dt$N[1],Q2=dt$N[2],Q3=dt$N[3],Q4=dt$N[4],Q5=dt$N[5])
}else{
dd <- list(Q1=NA,Q2=NA,Q3=NA,Q4=NA,Q5=NA) }
return(dd)
}
我有以下解决方案，但它不起作用。
finalTable <- TableA[,c('Q1','Q2','Q3','Q4','Q5') := mapply(function(a,b,c,d,e,f,g,h) Quadrants(TableB[, .SD[x %between% c(a,b) & y %between% c(c,d) & speed == h]], radius=e, centerX = f, centerY = g),minX,maxX,minY,maxY,r,cX,cY,speed)]
我不认为我做得对。因为下面的结果不是预期的结果。
speed minX maxX minY maxY r cX cY indx Q1 Q2 Q3 Q4 Q5
1: 42 1 10 1 10 5 6 6 1 32 32 100 68 68
2: 42 2 11 1 10 5 7 6 2 32 32 100 68 68
3: 42 3 12 1 10 5 8 6 3 32 32 100 68 68
4: 43 4 13 1 10 5 9 6 4 32 32 100 68 68
...
11: 42 11 20 1 10 5 16 6 11 32 32 100 68 68
12: 42 12 21 1 10 5 17 6 12 32 32 100 68 68
13: 43 1 10 1 10 5 6 6 13 32 32 100 68 68
14: 43 2 11 1 10 5 7 6 14 32 32 100 68 68
15: 43 3 12 1 10 5 8 6 15 32 32 100 68 68
...
22: 43 10 19 1 10 5 15 6 22 32 32 100 68 68
23: 43 11 20 1 10 5 16 6 23 32 32 100 68 68
24: 43 12 21 1 10 5 17 6 24 32 32 100 68 68
25: 44 1 10 1 10 5 6 6 25 32 32 100 68 68
26: 44 2 11 1 10 5 7 6 26 32 32 100 68 68
27: 44 3 12 1 10 5 8 6 27 32 32 100 68 68
28: 42 4 13 1 10 5 9 6 28 32 32 100 68 68
...
35: 44 11 20 1 10 5 16 6 35 32 32 100 68 68
36: 44 12 21 1 10 5 17 6 36 32 32 100 68 68
任何人都可以看看。我真的很感激。
预期输出：
speed minX maxX minY maxY r cX cY indx Q1 Q2 Q3 Q4 Q5
1: 42 2 11 1 10 5 7 6 1 200 100 400 100 200
2: 42 3 12 1 10 5 8 6 2 200 100 300 100 200
3: 42 4 13 1 10 5 9 6 3 200 100 300 100 100
4: 42 5 14 1 10 5 10 6 4 100 200 300 NA 100
...
11: 42 12 21 1 10 5 17 6 11 NA NA NA NA NA
12: 42 13 22 1 10 5 18 6 12 NA NA NA NA NA
13: 43 2 11 1 10 5 7 6 13 200 100 400 100 200
14: 43 3 12 1 10 5 8 6 14 200 100 300 100 200
15: 43 4 13 1 10 5 9 6 15 200 100 300 100 100
...
22: 43 11 20 1 10 5 16 6 22 NA NA NA NA 100
23: 43 12 21 1 10 5 17 6 23 NA NA NA NA NA
24: 43 13 22 1 10 5 18 6 24 NA NA NA NA NA
25: 44 2 11 1 10 5 7 6 25 200 100 400 100 200
26: 44 3 12 1 10 5 8 6 26 200 100 300 100 200
27: 44 4 13 1 10 5 9 6 27 200 100 300 100 100
28: 44 5 14 1 10 5 10 6 28 100 200 300 NA 100
...
35: 44 12 21 1 10 5 17 6 35 NA NA NA NA NA
36: 44 13 22 1 10 5 18 6 36 NA NA NA NA NA