R help - Sep 2010 - colorRamp of image to span larger range than dataset

Hello and thanks in advance,

Using the dataset volcano:
ascols =
colorRampPalette(c("gray","yellow","darkgoldenrod1","orange","red"),interpolate="spline")
x <- 10*(1:nrow(volcano))
y <- 10*(1:ncol(volcano))
image(x, y, volcano, col = ascols, axes = FALSE)

In the example above, how would I change my colorRampPalette or image
function so that it would span to 300 even though max(volcano)  = 195?
The image I want to make should not return any red because it does not
reach the true maximum possible value which is 300.


Thanks,
Daisy



--
Room E8C156
Dept. Biological Sciences
Macquarie University? NSW? 2109
Australia

colorRampPalette returns a function, not a list of colours.  You might want to
try something like:

ascols <-
    colorRampPalette(c("gray", "yellow",
"darkgoldenrod1", "orange", "red"),
interpolate="spline")
x <- 10*(1:nrow(volcano))
y <- 10*(1:ncol(volcano))
image(x, y, volcano, col = ascols(300), axes = FALSE)

### spot the difference... 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Daisy Englert Duursma
Sent: Monday, 6 September 2010 11:05 AM
To: r-help at r-project.org
Subject: [R] colorRamp of image to span larger range than dataset

Hello and thanks in advance,

Using the dataset volcano:
ascols =
colorRampPalette(c("gray","yellow","darkgoldenrod1","orange","red"),interpolate="spline")
x <- 10*(1:nrow(volcano))
y <- 10*(1:ncol(volcano))
image(x, y, volcano, col = ascols, axes = FALSE)

In the example above, how would I change my colorRampPalette or image
function so that it would span to 300 even though max(volcano)  = 195?
The image I want to make should not return any red because it does not
reach the true maximum possible value which is 300.


Thanks,
Daisy



--
Room E8C156
Dept. Biological Sciences
Macquarie University? NSW? 2109
Australia

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