Thanks Greg,
I'll give it a whirl and let you know how it goes (although it might not
be till after the bank holiday weekend now sorry for delay!)
Thanks for replying and spending time on this problem.
All the best,
Jenny
On Thu, 1 May 2008, Greg Snow wrote:
Does the following do what you want (or at least move in that
direction)?
u <- array(NA,c(5,8))
t <- seq(from=0.5, to=0.11,length=15)
t2 <- seq(from=(-0.7),to=(-0.1),length=25)
u[1:15] <- t
u[16:40] <- t2
v <- array(NA,c(5,8))
y <- seq(from=(-0.9), to=(-0.01),length=40)
v[1:40] <- y
library(TeachingDemos)
library(maps)
map('state',col='grey')
lats <- seq( 27.5, 48.7, length=5 )
longs <- seq( -123, -73, length=8 )
x <- longs[ col(u) ]
y <- lats[ row(u) ]
speed <- sqrt( u*u+v*v )
dir <- atan2(v,u)
my.symbols(x,y,ms.arrows, angle=dir, r=speed, add=TRUE, length=.05)
Hope this helps,
--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
[EMAIL PROTECTED]
(801) 408-8111
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jenny Barnes
Sent: Tuesday, April 29, 2008 6:26 AM
To: Jim Lemon
Cc: r-help@r-project.org
Subject: Re: [R] How to plot wind direction and strength field
Thanks Jim - here is some data:
u <- array(NA,c(5,8))
t <- seq(from=0.5, to=0.11,length=15)
t2 <- seq(from=(-0.7),to=(-0.1),length=25)
u[1:15] <- t
u[16:40] <- t2
v <- array(NA,c(5,8))
y <- seq(from=(-0.9), to=(-0.01),length=40) v[1:40] <- y
I've made up the data but it's similar magnitude and the
longitude direction is u and latitude direction is v as in
the real data.
I really appreciate your help!
Jenny
On Tue, 29 Apr 2008, Jim Lemon wrote:
Jenny Barnes wrote:
Hi Jim,
I would like to plot something like figure 2 on this webpage:
http://www.cnrfc.noaa.gov/storm_summaries/jan1997storms.php
My data is very large - covering the whole globe at 2.5deg
resolution
so
longitude=144 girds, latitude=73 grids and time=32 years - hard to
give you that data......Would it help to give you a couple of grid
squares worth of data for one year?
Okay, Figures 2 and 3 look like 5 degree squares, and given
a larger
plot,
2.5 degree should be okay. Do you want curved arrows? That
would take
some programming as the standard arrows are straight. Also,
the arrows
in the figures all seem to be the same length. I can make
the lengths
proportional to wind speed. Yes, some data would be helpful, as
getting the right plot usually involves trying out real
data. Doesn't
matter if it's faked as long as it has the same format and
similar numbers to the real thing.
Jim
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