[R] axis() after image.plot() does not work except if points() is inserted between

[Marc Girondot]

Thanks for the proposition. As you see bellow, par("usr") is the same 
before and after the points() (the full code is bellow):
....
 > par("usr")
[1] -0.2500000  1.2500000 -0.1666667  1.1666667
 > # if you remove this points() function, axis will show nothing.
 >
 > points(1.5, 1.5, type="p")
 > p2 <- par(no.readonly=TRUE)
 > par("usr")
[1] -0.2500000  1.2500000 -0.1666667  1.1666667
...

I can reproduce it in Ubuntu and MacosX R Gui and Rstudio (R 3.4.1).

Marc

Here is the code:
library(fields)
par(mar=c(5,4.5,4,7))
D <- matrix(c(10, 20, 25, 30, 12, 22, 32, 35, 13, 25, 38, 40), nrow=3)

p0 <- par(no.readonly=TRUE)
image.plot(D, col=rev(heat.colors(128)),bty="n", xlab="Lines",
            ylab="Columns", cex.lab = 0.5, zlim=c(min(D, na.rm=TRUE),max(D,
na.rm=TRUE)),
            las=1, axes=FALSE)
p1 <- par(no.readonly=TRUE)

par("usr")
par("xpd")

# if you remove this points() function, axis will show nothing.

points(1.5, 1.5, type="p")
p2 <- par(no.readonly=TRUE)
par("usr")
par("xpd")

##########
axis(1, at=seq(from=0, to=1, length=nrow(D)), labels=0:2, cex.axis=0.5)
axis(2, at=seq(from=0, to=1, length=ncol(D)), labels=0:3, las=1,
      cex.axis=0.5)

identical(p1, p2)




Le 24/07/2017 à 05:17, Jim Lemon a écrit :
> Hi marc,
> Try:
>
> par("usr")
>
> before and after the call to points and see if it changes.
>
> Jim
>
>
> On Sat, Jul 22, 2017 at 12:05 AM, Marc Girondot via R-help
> <r-help at r-project.org> wrote:
>> It is known (several discussions on internet) that axis() cannot be used
>> after fields:::image.plot() (axis() shows nothing).
>>
>> However, if points(1.5, 1.5, type="p") is inserted before the axis()
>> finctions, it works.
>>
>> I have investigated what points(1.5, 1.5, type="p") is doing to allow axis
>> to work and I don't find a solution. par() options are identical (p1 and p2
>> are identical).
>>
>> Has someone a solution ?
>>
>> Thanks
>>
>> Marc
>>
>> library(fields)
>> p0 <- par(no.readonly=TRUE)
>> image.plot(D, col=rev(heat.colors(128)),bty="n", xlab="Lines",
>>             ylab="Columns", cex.lab = 0.5, zlim=c(min(D, na.rm=TRUE),max(D,
>> na.rm=TRUE)),
>>             las=1, axes=FALSE)
>> p1 <- par(no.readonly=TRUE)
>>
>> # if you remove this points() function, axis will show nothing.
>>
>> points(1.5, 1.5, type="p")
>> p2 <- par(no.readonly=TRUE)
>>
>> ##########
>> axis(1, at=seq(from=0, to=1, length=nrow(D)), labels=0:2, cex.axis=0.5)
>> axis(2, at=seq(from=0, to=1, length=ncol(D)), labels=0:3, las=1,
>> cex.axis=0.5)
>>
>> identical(p1, p2)
>>
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