R help - Jul 2010 - Hydrology plots in R

Hello,

I am trying to create a plot often seen in hydrodynamic work than includes a
contour plot representing the water speed with arrows pointing in the
direction of flow. Does anyone have any idea how I might add arrows based on
wf$angle (in the example below) to the plot below?

Thanks in advance!

Sam

library(lattice)

speed <- runif(100, 0, 20)
wf <- data.frame(speed)
wf$width <- (1:10)
wf$length <- rep(1:10, each=10)
wf$angle <-runif(100, 0, 360)

#How do I add arrows based on wf$angle within each coloured box to represent
the direction of flow?
#i don't have to use lattice. Just using it as an example.
with(wf, contourplot(speed ~ width*length,
                     region=TRUE,
                     contour=FALSE
                     ))

-- 
*****************************************************
Sam Albers
Geography Program
University of Northern British Columbia
3333 University Way
Prince George, British Columbia
Canada, V2N 4Z9
phone: 250 960-6777
*****************************************************

	[[alternative HTML version deleted]]

Sam,

I recommend taking a look at the ggplot2 package. This page from the
author's website contains an example of what I think you are trying to
achieve:

http://had.co.nz/ggplot2/geom_segment.html

Obviously, this would require doing the whole plot in ggplot2, but that's
not at all unpleasant. There's even a mailing list (on Google Groups) from
ggplot2 with lots of friendly people to help.

Best of luck,
Jonathan


On Thu, Jul 22, 2010 at 8:56 AM, Sam Albers
<tonightsthenight@gmail.com>wrote:
> Hello,
>
> I am trying to create a plot often seen in hydrodynamic work than includes
> a
> contour plot representing the water speed with arrows pointing in the
> direction of flow. Does anyone have any idea how I might add arrows based
> on
> wf$angle (in the example below) to the plot below?
>
> Thanks in advance!
>
> Sam
>
> library(lattice)
>
> speed <- runif(100, 0, 20)
> wf <- data.frame(speed)
> wf$width <- (1:10)
> wf$length <- rep(1:10, each=10)
> wf$angle <-runif(100, 0, 360)
>
> #How do I add arrows based on wf$angle within each coloured box to
> represent
> the direction of flow?
> #i don't have to use lattice. Just using it as an example.
> with(wf, contourplot(speed ~ width*length,
>                     region=TRUE,
>                     contour=FALSE
>                     ))
>
> --
> *****************************************************
> Sam Albers
> Geography Program
> University of Northern British Columbia
> 3333 University Way
> Prince George, British Columbia
> Canada, V2N 4Z9
> phone: 250 960-6777
> *****************************************************
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
	[[alternative HTML version deleted]]

On 07/23/2010 12:56 AM, Sam Albers wrote:
> Hello,
>
> I am trying to create a plot often seen in hydrodynamic work than includes
a
> contour plot representing the water speed with arrows pointing in the
> direction of flow. Does anyone have any idea how I might add arrows based
on
> wf$angle (in the example below) to the plot below?
>
> Thanks in advance!
>
> Sam
>
> library(lattice)
>
> speed<- runif(100, 0, 20)
> wf<- data.frame(speed)
> wf$width<- (1:10)
> wf$length<- rep(1:10, each=10)
> wf$angle<-runif(100, 0, 360)
>
> #How do I add arrows based on wf$angle within each coloured box to
represent
> the direction of flow?
> #i don't have to use lattice. Just using it as an example.
> with(wf, contourplot(speed ~ width*length,
>                       region=TRUE,
>                       contour=FALSE
>                       ))
>
Hi Sam,
Try this solution from the plotrix package:

par(mar=c(5,4,4,4))
color2D.matplot(matrix(wf$speed,ncol=10),extremes=c("#88eeee","#ee88ee"))
color.legend(10.6,0,11.1,10,seq(-5,25,by=5),color.scale(seq(-5,25,by=5),
  extremes=c("#88eeee","#ee88ee")),gradient="y")
vectorField(matrix(wf$angle,ncol=10),matrix(0.5,nrow=10,ncol=10),
  xpos=matrix(0.5:9.5,nrow=10,ncol=10,byrow=TRUE),
  ypos=matrix(9.5:0.5,nrow=10,ncol=10),scale=0.5,vecspec="deg")

I probably don't have the values lined up correctly.

Jim

On Thu, Jul 22, 2010 at 7:56 AM, Sam Albers <tonightsthenight at
gmail.com> wrote:
> Hello,
>
> I am trying to create a plot often seen in hydrodynamic work than includes
a
> contour plot representing the water speed with arrows pointing in the
> direction of flow. Does anyone have any idea how I might add arrows based
on
> wf$angle (in the example below) to the plot below?
>
> Thanks in advance!
>
> Sam
>
> library(lattice)
>
> speed <- runif(100, 0, 20)
> wf <- data.frame(speed)
> wf$width <- (1:10)
> wf$length <- rep(1:10, each=10)
> wf$angle <-runif(100, 0, 360)
>
> #How do I add arrows based on wf$angle within each coloured box to
represent
> the direction of flow?
> #i don't have to use lattice. Just using it as an example.
> with(wf, contourplot(speed ~ width*length,
> ? ? ? ? ? ? ? ? ? ? region=TRUE,
> ? ? ? ? ? ? ? ? ? ? contour=FALSE
> ? ? ? ? ? ? ? ? ? ? ))

with(wf,
     levelplot(speed ~ width * length,
               angle = angle / 2 * pi,
               region = TRUE,
               contour = FALSE,
               panel = function(x, y, ..., subscripts, angle, scale = 0.45) {
                   panel.levelplot(x, y, ..., subscripts = subscripts)
                   panel.arrows(x[subscripts], y[subscripts],
                                x[subscripts] + scale * cos(angle[subscripts]),
                                y[subscripts] + scale * sin(angle[subscripts]),
                                length = 0.07)
               }))

-Deepayan