Status: open Group: Created: Sun May 28, 2017 10:35 AM UTC by l1q1d Last Updated: Sun May 28, 2017 10:35 AM UTC Owner: nobody
Hi, do you have any idea how to have log color in colormap/plshade/colorbar?
I have CC'd my response to your support request to the plplot-general
mailing list. Since that is our preferred support mechanism (to
collect support requests and the discussion of them all in one place),
I ask that you subscribe to that mailing list (see directions at https://lists.sourceforge.net/lists/listinfo/plplot-general) and
follow up there with your (likely inevitable) supplementary PLplot
questions rather than on this deprecated support request tracker.
That is an interesting question concerning color map 1 (N.B. not color map
0 since that is for discontinuous colors). The independent variable of
cmap1 ranges from 0 to 1 (inclusive). We have no switch to interpret
cmap1 values as logs, but that is not necessary since you
can do that conversion yourself. For example, suppose you have an
array z of 3rd coordinates which you would like to represent as a cmap1
color. Then try this transform:
c = log(z/zmax)/log(zmax/zmin) + 1
That c array is proportional to log z as you require, but due to
the linear transformation all values of that array are in the correct cmap1 range from
0 to 1 as you can see by substituting z=zmax where c = 1 and z=zmin
where c = 0 on the RHS.
So use that transformed c array or value anywhere (e.g., plshade,
plshades, plcol1, plcolorbar) that a cmap1 color map value can be
used, and you should be OK. However, as far as I know nobody has ever
tried this so I would appreciate you following up (on the
plplot-general mailing list) with your results (whether good or bad)
for the benefit of both our developers and ordinary users.
Alan
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
On 2017-05-28 10:35-0000 l1q1d wrote:
I have CC'd my response to your support request to the plplot-general
mailing list. Since that is our preferred support mechanism (to
collect support requests and the discussion of them all in one place),
I ask that you subscribe to that mailing list (see directions at
https://lists.sourceforge.net/lists/listinfo/plplot-general) and
follow up there with your (likely inevitable) supplementary PLplot
questions rather than on this deprecated support request tracker.
That is an interesting question concerning color map 1 (N.B. not color map
0 since that is for discontinuous colors). The independent variable of
cmap1 ranges from 0 to 1 (inclusive). We have no switch to interpret
cmap1 values as logs, but that is not necessary since you
can do that conversion yourself. For example, suppose you have an
array z of 3rd coordinates which you would like to represent as a cmap1
color. Then try this transform:
c = log(z/zmax)/log(zmax/zmin) + 1
That c array is proportional to log z as you require, but due to
the linear transformation all values of that array are in the correct cmap1 range from
0 to 1 as you can see by substituting z=zmax where c = 1 and z=zmin
where c = 0 on the RHS.
So use that transformed c array or value anywhere (e.g., plshade,
plshades, plcol1, plcolorbar) that a cmap1 color map value can be
used, and you should be OK. However, as far as I know nobody has ever
tried this so I would appreciate you following up (on the
plplot-general mailing list) with your results (whether good or bad)
for the benefit of both our developers and ordinary users.
Alan
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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