The shading in the graph of the curve xy in R

Question

I have data similar to the following:

X <- 1:20 B <- c(1,4,6,3,1, 4, 5,8,8,6,3,2,1, 1,5,7,8,6,4,2) C <- B + 4 myd <- data.frame (X, B, C) 

I want to shade with a different color inside the curve. Please note that filling the colors in x

 region 1 = 1 to 6 region 2 = 6 to 16 region 3 = 16 to 20 

Answer 1

Here is a solution with ggplot2.

 library(ggplot2) library(reshape2) d <- melt(myd, id.vars="X") d <- rbind( transform( d[ 0 <= d$X & d$X <= 6, ], interval=1 ), transform( d[ 6 <= d$X & d$X <= 16, ], interval=2 ), transform( d[ 16 <= d$X & d$X <= 20, ], interval=3 ) ) # Set the order in which we fill the areas: # first the large ones ("C"), then the small ones ("B"); # Otherwise, the small ones are invisible. d$variable <- LETTERS[3-as.numeric(d$variable)] # Alphabetic order ggplot( d, aes(X,value,fill=paste(variable,interval)) ) + # Set the alpha to a value close to 1, to see if the order is wrong geom_area(position="identity", alpha=.9) + opts(legend.position = "none") 

Answer 2

Just demonstrate section 1: 6:

 R> plot(X, B, type="l", col="blue", xlim=c(0, 25), ylim=c(0, 15)) R> par(new=TRUE) R> plot(X, C, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) R> polygon(c(1:6, 6:1), c(B[1:6], C[6:1]), col="purple") 

Answer 3

Based on Gong-Yi's answer, although I need to change the data to fill the bottom polygon. The full answer is:

 X <- 1:20 B <- c(1,4,6,3,1, 4, 5,8,8,6,3,2,1, 1,5,7,8,6,4,2) C <- B + 4 A <- rep (0, length(B)) myd <- data.frame (X, B, C, A) plot(X, B, type="l", col="blue", xlim=c(0, 25), ylim=c(0, 15)) # 1 to 6 par(new=TRUE) plot(X, C, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(1:6, 6:1), c(B[1:6], C[6:1]), col="green1") par(new=TRUE) plot(X, B, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(1:6, 6:1), c(B[1:6], A[6:1]), col="green4") # 6 to 16 par(new=TRUE) plot(X, C, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(6:16, 16:6), c(B[6:16], C[16:6]), col="blue1") par(new=TRUE) plot(X, B, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(6:16, 16:6), c(B[6:16], A[16:6]), col="blue4") # 16 to 20 par(new=TRUE) plot(X, C, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(16:20, 20:16), c(B[16:20], C[20:16]), col="purple1") par(new=TRUE) plot(X, B, type="l", col="red", xlim=c(0, 25), ylim=c(0, 15)) polygon(c(16:20, 20:16), c(B[16:20], A[20:16]), col="purple4")