You are drawing the line to the center of the plot (which is 0 be design).
What you actually want is to plot segments to the min(z) value.
Example:
Z <- matrix(1:9, 3)
surf <- persp(1:3, 1:3, Z)
points(trans3d(x=2, y=2, z=5, surf), col="red", pch=19)
from <- trans3d(x=2, y=2, z=5, surf)
to <- trans3d(x=2, y=2, z=min(Z), surf)
segments(from$x, from$y, to$x, to$y, col="red", lwd=2)
Uwe Ligges
On 13.06.2011 22:01, Tarmo Remmel wrote:> Hello,
>
> I have a matrix [9,11] called tempmed from which I produce a perspective
> plot. I then indicate a point on the surface to which I want to drop a
> point using points() and trans3d(). The code is below. However, the
> dropped line does not draw properly on the plot, it only comes down about
> half way through the vertical space. Is there a way to make this dropped
> line from a point hit the surface, or at least draw to the bottom of the
> plot?
>
> Using R 2.12.1 for PC.
>
> Thanks,
>
> Tarmo
>
>
>
>> tempmed
> [,1] [,2] [,3] [,4] [,5]
> [1,] 0.001953125 0.001953125 0.001953125 0.001953125 0.002197266
> [2,] 0.005371094 0.005371094 0.005615234 0.005615234 0.006103516
> [3,] 0.018798828 0.019042969 0.019042969 0.019775391 0.020019531
> [4,] 0.160522461 0.155517578 0.147460938 0.137695312 0.131225586
> [5,] 0.484130859 0.482421875 0.480712891 0.479003906 0.475463867
> [6,] 0.598144531 0.597656250 0.597412109 0.597167969 0.596923828
> [7,] 0.699707031 0.699707031 0.699707031 0.699462891 0.699462891
> [8,] 0.800048828 0.800048828 0.800048828 0.800048828 0.800048828
> [9,] 0.899902344 0.899902344 0.899902344 0.899902344 0.899902344
> [,6] [,7] [,8] [,9] [,10]
> [1,] 0.002197266 0.002441406 0.002685547 0.003173828 0.004150391
> [2,] 0.006347656 0.006835938 0.007568359 0.009033203 0.011596680
> [3,] 0.020996094 0.021972656 0.023925781 0.026611328 0.033935547
> [4,] 0.127319336 0.125610352 0.121459961 0.119140625 0.129638672
> [5,] 0.471557617 0.469482422 0.464355469 0.455200195 0.443115234
> [6,] 0.595947266 0.595458984 0.594238281 0.592285156 0.589843750
> [7,] 0.699462891 0.699218750 0.698974609 0.698486328 0.697631836
> [8,] 0.800048828 0.800048828 0.800048828 0.799804688 0.799560547
> [9,] 0.899902344 0.899902344 0.899902344 0.899902344 0.899902344
> [,11]
> [1,] 0.01855469
> [2,] 0.05310059
> [3,] 0.11010742
> [4,] 0.21472168
> [5,] 0.39318848
> [6,] 0.56079102
> [7,] 0.68554688
> [8,] 0.79589844
> [9,] 0.89916992
>>
>> persp(tempmed, ticktype="detailed", cex.axis=0.7,
zlab="Metric",
> ylab="Proportion", xlab="Rho", theta=-45)
>> surf<- persp(tempmed, ticktype="detailed", cex.axis=0.7,
zlab="Metric",
> ylab="Proportion", xlab="Rho", theta=-45)
>> points(trans3d(x=0.2, y=0.7, z=max(tempmed), surf),
col="red", pch=19,
> type="b")
>> points(trans3d(x=0.2, y=0.7, z=max(tempmed), surf),
col="red", pch=19,
> type="h")
>>
>
>
> _____________________________________
> Tarmo K Remmel PhD
> Associate Professor, Department of Geography
> York University, N413A Ross Building
> 4700 Keele Street, Toronto, Ontario, M3J 1P3
> Tel: 416-736-2100 x22496, Fax: 416-736-5988
> Skype: tarmoremmel
>
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