How to create Lines connecting two points in R

Question

Is there any way to create lines in R connecting two points? I am aware of lines(), function, but it creates line segment what I am looking for is an infinite length line.

Maybe `abline`? https://stat.ethz.ch/R-manual/R-devel/library/graphics/html/abline.html — Marta, Jan 07 '16 at 14:56
Thanks for the reply, but I was not looking for abline. I like to move parametrically in vector space rather than a coordinate geometry (y=mx+c) solution. — Udayan Maurya, Jan 08 '16 at 16:11

score 6 · Accepted Answer · answered Jan 07 '16 at 15:43

6

Here's an example of Martha's suggestion:

set.seed(1)
x <- runif(2)
y <- runif(2)

# function
segmentInf <- function(xs, ys){
  fit <- lm(ys~xs)
  abline(fit)
}

plot(x,y)
segmentInf(x,y)

answered Jan 07 '16 at 15:43

Marc in the box

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Thanks, I believe creating a self-defined function like this is the best solution. Probably R does not have any such predefined function. – Udayan Maurya Jan 08 '16 at 16:13
I have up voted but my level is 11 right now. Once I reach 15 the vote will be applicable. – Udayan Maurya Jan 18 '16 at 10:17

score 3 · Answer 2 · answered Jan 07 '16 at 15:42

3

#define x and y values for the two points
x <- rnorm(2)
y <- rnorm(2)
slope <- diff(y)/diff(x)
intercept <- y[1]-slope*x[1]
plot(x, y)
abline(intercept, slope, col="red")
# repeat the above as many times as you like to satisfy yourself

answered Jan 07 '16 at 15:42

doctorG

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score 1 · Answer 3 · 2016-01-07T17:21:48.713

1

Use segment() function.

#example    
x1 <- stats::runif(5)
x2 <- stats::runif(5)+2
y <- stats::rnorm(10)


plot(c(x1,x2), y)


segments(x1, y[1:5], x2, y[6:10], col= 'blue')

edited Jan 07 '16 at 17:21

answered Jan 07 '16 at 17:10

Thanks, but i was not looking for segments. – Udayan Maurya Jan 08 '16 at 16:14
why you dont want segments ? – Jan 08 '16 at 20:15

How to create Lines connecting two points in R

3 Answers3