Re: [Gnuplot-py-users] gnuplot.py and pm3d with 4d data

[Michael H. <mh...@ka...>]

To get blank lines in the data that is sent to gnuplot, put your data 
into a 3-d array then pass the array to Gnuplot.Data.  In other words, 
you currently have

x = [1,1,1,2,2,2,3,3,3,4,4,4]
y = [1,2,3,1,2,3,1,2,3,1,2,3]
z = [z(1,1),z(1,2),z(1,3),z(2,1),...]
val = [val(1,1), ...]

Instead, create an array as follows:

data = [
    [
        [1,1,z(1,1),val(1,1)],
        [1,2,z(1,2),val(1,2)],
        [1,3,z(1,3),val(1,3)],
    ],
    [
        [2,1,z(2,1),val(2,1)],
        [2,2,z(2,2),val(2,2)],
        [2,3,z(2,3),val(2,3)],
    ],
    ...
    ]

Then plot the data with

    resG.splot(Gnuplot.Data(data))

You could create the data array from your old lists using something like 
(untested!):

    data = Numeric.asarray([x,y,z,val], Numeric.Float32)
    # Change the order of the indices to "zip" the arrays together:
    data = Numeric.transpose(set, (1,0))
    data = Numeric.reshape((4,3,4,), data)

If you generate the data using functions (and if you are using python 2 
or above), an even easier way would be to use

    data = [[[x,y,z(x,y),val(x,y)] for y in yvals] for x in xvals]

Hope that helps.
Michael

Marc Hodapp wrote:

> when using gnuplot directly,  I can create 4d data plots with 
> something like:
>
>    set pm3d
>    splot 'file.dat' using 1:2:3:4
>
> Where file.dat is the data file, 1,2,3 are the columns with the x,y,z 
> data and 4 is the column with the value data which defines the color 
> value.
>
> Now I want to do the same thing using gnuplot.py. In my python 
> program, I define 4 lists: x, y,z,val.  I then use the instructions:
>
>    resG = Gnuplot.Gnuplot()
>    resG('set pm3d')
>    resG.splot(Gnuplot.Data(x,y,z,val))
>
> What I get as a result, is a 3d plot with my points, but no colored 
> surface showing val . So my questions are: Can Gnuplot.Data() receive 
> 4 arguments, which are then passed to splot and pm3d? When using 
> gnuplot directly, the file must contain blank lines between two scans 
> (isolines). In gnuplot.py do I have to include empty strings in the  
> x,y,z,val lists to delimit the isolines? How can I delimit these scans 
> in gnuplot.py? Is there an other way to plot my surface using the 
> xyz,val lists ( like resG('splot ...') )?


-- 
Michael Haggerty
mh...@al...