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graphing inequalities (intervals) in one varible

7 messages · AbouEl-Makarim Aboueissa, Mattson, Todd, R. Michael Weylandt +2 more

Original
Mattson, Todd
# 
You may want to try the curve function.  For example:

curve(x^2,-1,1,xlim=c(-3,5),ylim=c(0,9))
 curve(x^2,2,3,add=TRUE)

Todd Mattson
DeVry University

-----Original Message-----
From: r-sig-teaching-bounces at r-project.org [mailto:r-sig-teaching-bounces at r-project.org] On Behalf Of Yahoo!
Sent: Wednesday, May 08, 2013 6:10 AM
To: r-sig-teaching at r-project.org
Subject: [R-sig-teaching] graphing inequalities (intervals) in one varible

Dear All:

It seems a very silly question. But I never tried it before. I am teaching a college algebra class this summer. 

I need some help with graphing intervals on the real line. For examples:

{x | -7<= x < 5 and x > 7}

{x | x > 3}

etc...


thank you very much
abou

========================

AbouEl-Makarim Aboueissa

Sozan Elsalakawy

Mohamed Agamia



246 Auburn Street, #158

Portland, ME 04103

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Tel: (207) 797-2724

Email: aboueiss at yahoo.com

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R. Michael Weylandt
# 
Here's the start of a function. I'll leave it to you to do it better
(it should probably also use S4 methods, but that's another project):

interval <- function(lower = -Inf, upper = Inf, lower_closed = FALSE,
upper_closed = FALSE){
  structure(.Data = NULL, lower = lower, upper = upper, lower_closed =
lower_closed, upper_closed = upper_closed, class = 'interval')
}

plot.interval <- function(x){
 l <- attr(x, "lower")
 u <- attr(x, "upper")

 r <- c(l, u) * c(if(l > 0) 0.7 else 1.2, if(u > 0) 1.2 else 0.7)
 plot(r, c(0,1), main = '', bty = 'n', xlab = '', ylab = '', yaxt =
'n', type = 'n', xaxt = 'n')

 axis(1, at = seq(r[1], r[2], length.out = 10))

 lines(c(l, u), c(0.5, 0.5), col = 2, lwd = 2)

 lc <- attr(x, 'lower_closed')
 uc <- attr(x, 'upper_closed')


 points(c(l, u), c(0.5, 0.5), pch = c(1, 19)[c(lc, uc) + 1], col = 2, cex = 2)

}
On Wed, May 8, 2013 at 12:10 PM, Yahoo! <aboueiss at yahoo.com> wrote:
Gabor Grothendieck
#
On Wed, May 8, 2013 at 7:10 AM, Yahoo! <aboueiss at yahoo.com> wrote:
Check out the intervals packages:

library(intervals)
example(plot.Intervals)

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