[R] Line color based on data values?

[Daniel Malter]

Hi,

for example:

today=rnorm(100)
yesterday=rnorm(100)
up=today[today>yesterday]
down=today[today<yesterday]
index.up=which(today>yesterday)
index.down=which(today<yesterday)

plot(up~yesterday[index.up],col="green",xlim=c(-5,5),ylim=c(-5,5))
points(down~yesterday[index.down],col="red")


today: today's returns
yesterday: yesterday's return
up: returns if returns today are greater than yesterday
down: return if returns are smaller than yesterday
(for pairs of observations)

index.up: index number of observations for which up==true
index.down: index number of obersvations for which down=true

plot: first plot today's returns against yesterday's returns
for stocks that are up only (adjust plotting limits of x and y axis so as
to accomodate the later plot of down stocks; plot ups in green)

points: plot today's return against yesterday's returns for stocks that are
down only (plot in the same plot generated above; plot in red)

Cheers,
Daniel


-------------------------
cuncta stricte discussurus
-------------------------

-----Ursprüngliche Nachricht-----
Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
Auftrag von Rory.WINSTON at rbs.com
Gesendet: Tuesday, November 25, 2008 12:35 PM
An: r-help at r-project.org
Betreff: [R] Line color based on data values?

Hi all

Does anyone know if it is possible when plotting a line or scatter plot, to
selectively color the data points based on the data value? i.e. if plotting
say the percentage change in stock price movements, to color +ve points in
green and -ve points in red? And extending this to a user-defined range of
colors based on the quartile of the data points?

Thanks
Rory

Rory Winston
RBS Global Banking & Markets
280 Bishopsgate, London, EC2M 4RB
Office: +44 20 7085 4476



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