R help - Aug 2012 - legend position help

Hi there,

I draw a multiple figure in one plot, like the following:

par(mfcol=c(1,5),mar=c(4,4,0,0)+0.2, oma=c(0,0,3,0))
plot(1:10, type = "b")
plot(1:10, type = "b")
plot(1:10, type = "b")
plot(1:10, type = "b")
plot(1:10, type = "b")

Now, I hope to plot the legend like the following:

legend("top", legend=c("Example"), pch = 21, lty = 1, merge
= FALSE,
horiz = TRUE, bty="n", xpd = NA)

There were two problems:

1) the legend is put inside the fifth figure instead of the top center 
of the whole plot, i.e., the center of the outer top margin.

Now, I use a stupid solution, I replace "top" in the above command
with
locator(1). However, using this solution, the plot have to be in an 
interactive mode, and the position is not accuracy.

2) the point is connected with the line in the legend. I hope there is a 
space between the two symbols, like --- o instead of  ---o. If possible, 
put the point before the line, like o ----. Unfortunately, I don't find 
any way to do that.

Any suggestion will be greatly appreciated.

Regards,
Jinsong

You can use the grconvertY function to find the position in the
current user coordinates that corresponds to the top of the device
area (instead of using locator).

Look at the "merge" argument to the legend  function.

On Wed, Aug 15, 2012 at 10:04 AM, Jinsong Zhao <jszhao at yeah.net>
wrote:
> Hi there,
>
> I draw a multiple figure in one plot, like the following:
>
> par(mfcol=c(1,5),mar=c(4,4,0,0)+0.2, oma=c(0,0,3,0))
> plot(1:10, type = "b")
> plot(1:10, type = "b")
> plot(1:10, type = "b")
> plot(1:10, type = "b")
> plot(1:10, type = "b")
>
> Now, I hope to plot the legend like the following:
>
> legend("top", legend=c("Example"), pch = 21, lty = 1,
merge = FALSE, horiz > TRUE, bty="n", xpd = NA)
>
> There were two problems:
>
> 1) the legend is put inside the fifth figure instead of the top center of
> the whole plot, i.e., the center of the outer top margin.
>
> Now, I use a stupid solution, I replace "top" in the above
command with
> locator(1). However, using this solution, the plot have to be in an
> interactive mode, and the position is not accuracy.
>
> 2) the point is connected with the line in the legend. I hope there is a
> space between the two symbols, like --- o instead of  ---o. If possible,
put
> the point before the line, like o ----. Unfortunately, I don't find any
way
> to do that.
>
> Any suggestion will be greatly appreciated.
>
> Regards,
> Jinsong
>
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-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com