How to add two regression linear equations and R2 with each face?

Question

I would like to add two regression line equations and R2s with each face. I adopted the Jayden function to solve this problem, but I found that each equation was the same. The likely reason is sending the wrong subset of data to the function. Any advice would be appreciated!

My code is:

p <- ggplot(data=df,aes(x=x))+ geom_point(aes(y = y1),size=2.0)+ geom_smooth(aes(y = y1),method=lm,se=FALSE,size=0.5, fullrange = TRUE)+ # Add regression line; annotate("text",x = 150,y =320, label = lm_eqn(lm(y1~x,df)), # maybe wrong size = 2.0, parse = TRUE)+ # Add regression line equation; geom_point(aes(y = y2),size=2.0)+ geom_smooth(aes(y = y2),method=lm,se=FALSE,size=0.5, fullrange = TRUE)+ # Add regression line; annotate("text",x = 225,y =50, label = lm_eqn(lm(y2~x,df)), size = 2.0, parse = TRUE)+ # Add regression line equation; facet_wrap(~trt) 

My info frame:

 x y1 y2 trt 22.48349 34.2 31.0 6030 93.52976 98.5 96.0 6030 163.00984 164.2 169.8 6030 205.62072 216.7 210.0 6030 265.46812 271.8 258.5 6030 23.79859 35.8 24.2 6060 99.97307 119.4 90.6 6060 189.91814 200.8 189.3 6060 268.10060 279.5 264.6 6060 325.65609 325.7 325.4 6060 357.59726 353.6 353.8 6060 

My plot:

PS. There are two lines and your equations in each face, and two lines are correct, but two equations are wrong. Obviously, the upper / lower equations in the right and left sides must be different from each other.

Answer 1

1) ggplot2 Try first converting df to a long form (see line ##). We create an annotation annotation data frame that defines the text and where it is used for use with geom_text . Note that since the graph is faceted by trt , geom_text will use the trt column in each ann row to associate this row with the corresponding face.

 library(ggplot2) library(reshape2) long <- melt(df, measure.vars = 2:3) ## trts <- unique(long$trt) ann <- data.frame(x = c(0, 100), y = c(250, 100), label = c(lm_eqn(lm(y1 ~ x, df, subset = trt == trts[1])), lm_eqn(lm(y2 ~ x, df, subset = trt == trts[1])), lm_eqn(lm(y1 ~ x, df, subset = trt == trts[2])), lm_eqn(lm(y2 ~ x, df, subset = trt == trts[2]))), trt = rep(trts, each = 2), variable = c("y1", "y2")) ggplot(long, aes(x, value)) + geom_point() + geom_smooth(aes(col = variable), method = "lm", se = FALSE, full_range = TRUE) + geom_text(aes(x, y, label = label, col = variable), data = ann, parse = TRUE, hjust = -0.1, size = 2) + facet_wrap(~ trt) 

ann could be equivalently defined as follows:

 f <- function(v) lm_eqn(lm(value ~ x, long, subset = variable==v[[1]] & trt==v[[2]])) Grid <- expand.grid(variable = c("y1", "y2"), trt = trts) ann <- data.frame(x = c(0, 100), y = c(250, 100), label = apply(Grid, 1, f), Grid) 

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2) the lattice . Perhaps, in this case, perhaps the lattice:

 library(lattice) xyplot(y1 + y2 ~ x | factor(trt), df, key = simpleKey(text = c("y1", "y2"), col = c("blue", "red")), panel = panel.superpose, panel.groups = function(x, y, group.value, ...) { if (group.value == "y1") { X <- 150; Y <- 300; col <- "blue" } else { X <- 250; Y <- 100; col <- "red" } panel.points(x, y, col = col) panel.abline(lm(y ~ x), col = col) panel.text(X, Y, parse(text = lm_eqn(lm(y ~ x))), col = col, cex = 0.7) } ) 

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3) latticeExtra or we could make the lattice graph more ggplot2-like:

 library(latticeExtra) xyplot(y1 + y2 ~ x | factor(trt), df, par.settings = ggplot2like(), key = simpleKey(text = c("y1", "y2"), col = c("blue", "red")), panel = panel.superpose, panel.groups = function(x, y, group.value, ...) { if (group.value == "y1") { X <- 150; Y <- 300; col <- "blue" } else { X <- 250; Y <- 100; col <- "red" } panel.points(x, y, col = col) panel.grid() panel.abline(lm(y ~ x), col = col) panel.text(X, Y, parse(text = lm_eqn(lm(y ~ x))), col = col, cex = 0.7) } ) 

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Note: We used this as df :

 df <- structure(list(x = c(22.48349, 93.52976, 163.00984, 205.62072, 265.46812, 23.79859, 99.97307, 189.91814, 268.1006, 325.65609, 357.59726), y1 = c(34.2, 98.5, 164.2, 216.7, 271.8, 35.8, 119.4, 200.8, 279.5, 325.7, 353.6), y2 = c(31, 96, 169.8, 210, 258.5, 24.2, 90.6, 189.3, 264.6, 325.4, 353.8), trt = c(6030L, 6030L, 6030L, 6030L, 6030L, 6060L, 6060L, 6060L, 6060L, 6060L, 6060L )), .Names = c("x", "y1", "y2", "trt"), class = "data.frame", row.names = c(NA, -11L)) 

Refresh

• Added colored text.
• Added alternative ann .
• Added lattice solution.
• Added lattice variable to solve lattice.