[R-sig-teaching] plot an angle of 450 degrees and adding a circular arrow to it

[Joel Schwartz]

Steven,

Change

abline(x1,y1, lwd = 3) to lines(x1,y1, lwd = 3) and you'll get the line you're looking for. abline is just for drawing a line with a given slope and intercept. lines is more general.

Also, c(-4*pi,-(7*pi)/2,-3*pi,-(5*pi)/2,-2*pi,-(3*pi)/2,-pi,-pi/2, 0,pi/2,pi,(3*pi)/2,2*pi,(5*pi)/2,3*pi,(7*pi)/2,4*pi)
can be done with a call to seq instead. For example:
seq(-4*pi, 4*pi, pi/2)

Best Wishes,
Joel


On Oct 21, 2014, at 11:30 AM, Steven Stoline <sstoline at gmail.com> wrote:

> Dear Jones:
> 
> Could you please look to this R code. I am trying to graph both sin(x+pi/6)
> and sin(x) in the same plot to show the shift. I used abline to graph the
> sin(x), but it looked like same as the x-axis.
> 
> 
> x<-seq(-2.2*pi,2*pi,0.01)
> y<-sin(x+pi/6)
> 
> 
> #### To draw a box of the graph:
> #### ==========================
> 
> plot(0:10, 0:10, type = "n", xaxt = "n", yaxs = "i", xaxs = "i", yaxt =
> "n", xlab = "", ylab = "")
> 
> plot(x, y, type='l', lwd = 3,  col="red", xaxt = "n", xlab="", ylab="")
> 
> 
> 
> #### abline(v=c(-4*pi,-(7*pi)/2,-3*pi,-(5*pi)/2,-2*pi,-(3*pi)/2,-pi,-pi/2,
> 0,pi/2,pi,(3*pi)/2,2*pi,(5*pi)/2,3*pi,(7*pi)/2,4*pi),col="blue")
> 
> 
> abline(h=0, lwd=3)
> abline(v=0, lwd=3)
> 
> 
> x1<-seq(0,2*pi,0.01)
> y1<-sin(x1)
> abline(x1,y1, lwd = 3)
> 
> 
> thank you very much
> Steven
> 
> 
> On Mon, Oct 20, 2014 at 1:08 PM, Steven Stoline <sstoline at gmail.com> wrote:
> 
>> Many thanks
>> 
>> it works
>> 
>> Steven
>> 
>> On Mon, Oct 20, 2014 at 11:17 AM, Albyn Jones <jones at reed.edu> wrote:
>> 
>>> Here is a quickly written and barely tested function.  You might want to
>>> add a final position vector,
>>> color, lwd, lty, etc.  It assumes the angle is given in degrees, and
>>> checks the sign of the angle to draw
>>> in the correct direction.
>>> 
>>> albyn
>>> =====================================================================
>>> 
>>> DrawAngle  <- function(theta,r=1){
>>>    # assumes angles given in degrees, not radians
>>>    theta <- 2*pi*theta/360
>>>    plot(0,0, xlim=c(-2,2),ylim=c(-2,2))
>>>    abline(h=0)
>>>    abline(v=0)
>>>    sgn <- 1
>>>    if(theta <0) {
>>>        sgn  <- -1
>>>        theta <- -theta
>>>        }
>>>    Theta <-  sgn*seq(0,theta,.01)
>>>    if(theta > 2*pi) r <- seq(1,1.1,along.with=Theta)
>>>    x <- r*cos(Theta)
>>>    y <- r*sin(Theta)
>>>    lines(x,y)
>>>    n <- length(x)
>>>    arrows(x[n-1],y[n-1],x[n],y[n])
>>> }
>>> 
>>> On Mon, Oct 20, 2014 at 1:47 AM, Steven Stoline <sstoline at gmail.com>
>>> wrote:
>>> 
>>>> Dear All:
>>>> 
>>>> I am wondering if someone can show me how to plot an angles around the
>>>> center of a unit circle with x-y vertices added to it.
>>>> 
>>>> Also how to add arrows showing the size and the direction of angle(s).
>>>> 
>>>> Examples: 135 degrees and 450 degrees angles.
>>>> 
>>>> with many thanks
>>>> Steven
>>>> 
>>>> --
>>>> Steven M. Stoline
>>>> 1123 Forest Avenue
>>>> Portland, ME 04112
>>>> sstoline at gmail.com
>>>> 
>>>>        [[alternative HTML version deleted]]
>>>> 
>>>> _______________________________________________
>>>> R-sig-teaching at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
>>>> 
>>> 
>>> 
>> 
>> 
>> --
>> Steven M. Stoline
>> 1123 Forest Avenue
>> Portland, ME 04112
>> sstoline at gmail.com
>> 
> 
> 
> 
> -- 
> Steven M. Stoline
> 1123 Forest Avenue
> Portland, ME 04112
> sstoline at gmail.com
> 
> 	[[alternative HTML version deleted]]
> 
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