A loop or something else for plotting using curve() in R

Question

I'm trying to draw 3 overlaying curves (please see my R code below) in any 3 different colors (e.g., red, green, blue). I have tried the following but don't get neatly shaped plots.

Could this be looped easily in "R base"? Or there are some other possibilities?

 N  <- c(120, 528, 828)
df1 <- c(3, 3, 3)
df2 <- c(108, 516, 816)
 f  <- c(20, 20, 20) 


## 3 Plots:

Likelihood = curve( df(f, df1, df2, ncp = (x * N) / (1 - x) ) ,
  col = 'red4', lwd = 3, from = 0, to = 1, n = 1e4)

spadarian · Accepted Answer · 2017-04-12 02:18:51Z

1

With a basic loop you could try something like:

for(i in 1:length(N)) {
    add <- if(i == 1) FALSE else TRUE
    curve( df(f[i], df1[i], df2[i], ncp = (x * N[i]) / (1 - x) ) ,
           col = i, lwd = 3, from = 0, to = 1, n = 1e4, add=add)
}

Not the prettiest but using the basics. You should definitely explore ggplot2.

To avoid that some curves not complete, you could first get the values for each curve, estimate their ranges and then plot them. For example:

# function to get the values of each curve
curve_ <- function(x, i) df(f[i], df1[i], df2[i], ncp = (x * N[i]) / (1 - x))

# estimate the values of each curve
curves <- lapply(1:length(N), function(i) {
    x <- seq(0,1,length.out = 1e4)
    curve_(x, i)
})

# estimate the ranges
ranges_ <- sapply(curves, range, na.rm=T)

# plot using the ranges as plotting parameters (ylim)
for (i in 1:length(curves)) {
    if(i == 1) {
        plot(curves[[i]], type='l', col=i, xlim=c(0,length(curves[[i]])), ylim=c(min(ranges_[1,]), max(ranges_[2,])))
    } else {
        lines(curves[[i]], col=i)
    }
}

edited Apr 12, 2017 at 2:18

answered Apr 12, 2017 at 2:02

spadarian

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5 Comments

rnorouzian Over a year ago

Thanks, is it possible to put the tallest one be plotted first and then the 2 other one be plotted after that?

rnorouzian Over a year ago

Thank you, for color changes, should I be defining a separate vector?

spadarian Over a year ago

Yes. You can define a vector with the colours and then use it with col=color_vector[i]

spadarian Over a year ago

for (i in 1:10) plot(rnorm(10))

rnorouzian Over a year ago

spadarian, can I send you an R file before asking a question, it is a loop question and everything works fine except when I want to get a png file for each "i", the png file come out blank?

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