Trying to use 4 column data for splot

[Randall L Rathbun]

I am trying to use splot to display 3 dimension data, with a colorspec in the 4th column.
For example, the first three lines of my "data" file read:

33.152 116.649 0.6 "0xFF0000"
33.150 116.654 0.8 "0xFD0402"
33.152 116.649 0.5 "0xFB0804"

The 4th column is a 24 bit RGB color value.
I have tried to set up the appropriate splot command, but I have been unable to get the plot line to satisfactorily display the data

% splot "data" using 1:2:3:4 with dots lw 5 rgbcolor variable

for example
What would be the correct way to do the splot line?

Thank you for your help.

[Hiroki Motoyoshi]

I think your plot isn’t working as expected due to two key points that need a small adjustment.

1. Use of "rgbcolor variable":
To specify point colors, you should use the linecolor option (abbreviated as lc) together with "rgbcolor variable". So make sure your plot command includes something like:

lc rgbcolor variable

2. Handling of the fourth column in "using":
In your data, the fourth column appears to be a hexadecimal color code in double quotes, like "0xFF0000". Gnuplot treats this as a string. However, when using "lc rgbcolor variable", Gnuplot expects a numeric color value (an integer).

To fix this, you can explicitly convert the string to an integer using "int(strcol(4))", like this:

splot "data" using 1:2:3:(int(strcol(4))) with dots lw 5 lc rgbcolor variable

Alternatively, if you're generating the data yourself, it's even better to write the color codes as unquoted numeric literals:

33.152 116.649 0.6 0xFF0000
33.150 116.654 0.8 0xFD0402
33.152 116.649 0.5 0xFB0804

With that format, the following will work just fine:

splot "data" using 1:2:3:4 with dots lw 5 lc rgbcolor variable

Hope this helps.