gnuplot-beta

RE: key error in 2D plot line with color palette by hon fui lee

[hon f. l. <ho...@gm...>]

Tried your suggestion. The "lc palette Z" introduces error like " line
XX: ';' expected".
"lc Z" is OK but not as palette, discrete color instead. Same as "lc
variable" Eg. of my Z value ranges from 0.105 to 0.331.

Let me give you a better example. A study on a group of university
student on their age and performance.
Student A: Age 21
Hour attending class subject 1= 10 hours : Score=70
Hour attending class subject 2= 12 hours : Score=80
.
.
.
.
Student B: Age 25
Hour attending class subject 1= 10 hours : Score 55
Hour attending class subject 2= 20 hours : Score 60
.
.
.
.

Let plot hour attending class subject (x) vs score (y). Each curve is
colored according to the age to see any trend.

In my earliest post, notice linespoints give correct color and symbol
according to the plot/key, just like the curve itself. Only the line
color is wrong.
If the plot can do color palette/gradient on the curve correctly(or
may be incorrectly) why not the key?


Thanks.

On Thursday 11 March 2010 23:30:28 hon fui lee wrote:
> I'm trying to do a 2D lines/linespoint plot with linecolor from 3rd
> column as color palette.
> All are OK except the key does not proper linecolor. See sample
> command file and sample output (pdf).
> I'm using gnuplot version 4.5 (development) on Windows.
>
> Is that a bug or feature? Thanks.

I think it is a mis-expectation.

Your lines happen to each have a constant Z value, which you can think of
as a color value, so for your particular plot each entire line is a
single color and it would make sense for the sample line segment in the
key to be that same color.

But how is gnuplot supposed to know this?  In general each point could
have a different Z value and each line would have many segments with
various colors.  Which of these colors would you put in the key?

If you know in advance that each line has a constant Z value, maybe
you can revise the plot command so that instead of
   plot 'foo' using 1:2:3 lc palette
you use
   Z = constant_z_for_this_line
   plot 'foo' using 1:2 lc palette Z

For this you would have to read in the Z values before issuing the
plot command.  That may or may not be possible in your particular
plotting scenario.

	Ethan

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-- 
hon_fui

Re: key error in 2D plot line with color palette by hon fui lee

[sfeam (E. Merritt) <eam...@gm...>]

On Sunday 14 March 2010, hon fui lee wrote:
> Tried your suggestion. The "lc palette Z" introduces error like " line
> XX: ';' expected".
> "lc Z" is OK but not as palette, discrete color instead. Same as "lc
> variable" Eg. of my Z value ranges from 0.105 to 0.331.

I was not clear enough.  Please see "help colorspec"

The idea is that the 'Z' in "lc palette Z" stands for either
"frac <value>" where <value> runs from 0 to 1 and represents
a sample on the current palette,  or "cb <value>" where
<value> is drawn from the range of the current colorbox.

> Let me give you a better example. A study on a group of university
> student on their age and performance.
> Student A: Age 21
> Hour attending class subject 1= 10 hours : Score=70
> Hour attending class subject 2= 12 hours : Score=80
> .
> .
> .
> .
> Student B: Age 25
> Hour attending class subject 1= 10 hours : Score 55
> Hour attending class subject 2= 20 hours : Score 60
> .
> .
> .
> .
> 
> Let plot hour attending class subject (x) vs score (y). Each curve is
> colored according to the age to see any trend.

Fine.  So let's assume your student's ages run from 20 to 30.
Then we have
   set cbrange [20:30]
   plot 'student1' using ... with lines lc cb 21,
        'student2' using ... with lines lc cb 25, 
		'student3' ...
and so on.
 
> In my earliest post, notice linespoints give correct color and symbol
> according to the plot/key, just like the curve itself. Only the line
> color is wrong.
> If the plot can do color palette/gradient on the curve correctly(or
> may be incorrectly) why not the key?
  
You have asked it to color the lines by z value.
Each point or line segment has a z value.
But what is the z value of the key?  It has none.

	Ethan

 
> Thanks.
> 
> On Thursday 11 March 2010 23:30:28 hon fui lee wrote:
> > I'm trying to do a 2D lines/linespoint plot with linecolor from 3rd
> > column as color palette.
> > All are OK except the key does not proper linecolor. See sample
> > command file and sample output (pdf).
> > I'm using gnuplot version 4.5 (development) on Windows.
> >
> > Is that a bug or feature? Thanks.
> 
> I think it is a mis-expectation.
> 
> Your lines happen to each have a constant Z value, which you can think of
> as a color value, so for your particular plot each entire line is a
> single color and it would make sense for the sample line segment in the
> key to be that same color.
> 
> But how is gnuplot supposed to know this?  In general each point could
> have a different Z value and each line would have many segments with
> various colors.  Which of these colors would you put in the key?
> 
> If you know in advance that each line has a constant Z value, maybe
> you can revise the plot command so that instead of
>    plot 'foo' using 1:2:3 lc palette
> you use
>    Z = constant_z_for_this_line
>    plot 'foo' using 1:2 lc palette Z
> 
> For this you would have to read in the Z values before issuing the
> plot command.  That may or may not be possible in your particular
> plotting scenario.
> 
> 	Ethan

Re: key error in 2D plot line with color palette by hon fui lee

[hon f. l. <ho...@gm...>]

OK, I understand the concept of key and curve point.

How can it be done in iteration?

Regards,

On Mon, Mar 15, 2010 at 11:27 AM, sfeam (Ethan Merritt)
<eam...@gm...> wrote:
> On Sunday 14 March 2010, hon fui lee wrote:
>> Tried your suggestion. The "lc palette Z" introduces error like " line
>> XX: ';' expected".
>> "lc Z" is OK but not as palette, discrete color instead. Same as "lc
>> variable" Eg. of my Z value ranges from 0.105 to 0.331.
>
> I was not clear enough.  Please see "help colorspec"
>
> The idea is that the 'Z' in "lc palette Z" stands for either
> "frac <value>" where <value> runs from 0 to 1 and represents
> a sample on the current palette,  or "cb <value>" where
> <value> is drawn from the range of the current colorbox.
>
>> Let me give you a better example. A study on a group of university
>> student on their age and performance.
>> Student A: Age 21
>> Hour attending class subject 1= 10 hours : Score=70
>> Hour attending class subject 2= 12 hours : Score=80
>> .
>> .
>> .
>> .
>> Student B: Age 25
>> Hour attending class subject 1= 10 hours : Score 55
>> Hour attending class subject 2= 20 hours : Score 60
>> .
>> .
>> .
>> .
>>
>> Let plot hour attending class subject (x) vs score (y). Each curve is
>> colored according to the age to see any trend.
>
> Fine.  So let's assume your student's ages run from 20 to 30.
> Then we have
>   set cbrange [20:30]
>   plot 'student1' using ... with lines lc cb 21,
>        'student2' using ... with lines lc cb 25,
>                'student3' ...
> and so on.
>
>> In my earliest post, notice linespoints give correct color and symbol
>> according to the plot/key, just like the curve itself. Only the line
>> color is wrong.
>> If the plot can do color palette/gradient on the curve correctly(or
>> may be incorrectly) why not the key?
>
> You have asked it to color the lines by z value.
> Each point or line segment has a z value.
> But what is the z value of the key?  It has none.
>
>        Ethan
>
>
>> Thanks.
>>
>> On Thursday 11 March 2010 23:30:28 hon fui lee wrote:
>> > I'm trying to do a 2D lines/linespoint plot with linecolor from 3rd
>> > column as color palette.
>> > All are OK except the key does not proper linecolor. See sample
>> > command file and sample output (pdf).
>> > I'm using gnuplot version 4.5 (development) on Windows.
>> >
>> > Is that a bug or feature? Thanks.
>>
>> I think it is a mis-expectation.
>>
>> Your lines happen to each have a constant Z value, which you can think of
>> as a color value, so for your particular plot each entire line is a
>> single color and it would make sense for the sample line segment in the
>> key to be that same color.
>>
>> But how is gnuplot supposed to know this?  In general each point could
>> have a different Z value and each line would have many segments with
>> various colors.  Which of these colors would you put in the key?
>>
>> If you know in advance that each line has a constant Z value, maybe
>> you can revise the plot command so that instead of
>>    plot 'foo' using 1:2:3 lc palette
>> you use
>>    Z = constant_z_for_this_line
>>    plot 'foo' using 1:2 lc palette Z
>>
>> For this you would have to read in the Z values before issuing the
>> plot command.  That may or may not be possible in your particular
>> plotting scenario.
>>
>>       Ethan
>



-- 
hon_fui

Re: key error in 2D plot line with color palette by hon fui lee

[hon f. l. <ho...@gm...>]

I finally got it. Here is the command

age = "20 21 22 23 24 25 26 ...." #add in more according to your taste
set palette rgbformulae 33,13,10
set cbrange [20:30]
color_age(n) = word(age,n)
title_x(n) = word(<sometitle>, n)
plot for [age=1:20] 'datafile.dat' index age-1 using 1:2 t
title_x(age) lc palette cb color_age(age)

Regards,
hon_fui


On Mon, Mar 15, 2010 at 3:39 PM, hon fui lee <ho...@gm...> wrote:
> OK, I understand the concept of key and curve point.
>
> How can it be done in iteration?
>
> Regards,
>
> On Mon, Mar 15, 2010 at 11:27 AM, sfeam (Ethan Merritt)
> <eam...@gm...> wrote:
>> On Sunday 14 March 2010, hon fui lee wrote:
>>> Tried your suggestion. The "lc palette Z" introduces error like " line
>>> XX: ';' expected".
>>> "lc Z" is OK but not as palette, discrete color instead. Same as "lc
>>> variable" Eg. of my Z value ranges from 0.105 to 0.331.
>>
>> I was not clear enough.  Please see "help colorspec"
>>
>> The idea is that the 'Z' in "lc palette Z" stands for either
>> "frac <value>" where <value> runs from 0 to 1 and represents
>> a sample on the current palette,  or "cb <value>" where
>> <value> is drawn from the range of the current colorbox.
>>
>>> Let me give you a better example. A study on a group of university
>>> student on their age and performance.
>>> Student A: Age 21
>>> Hour attending class subject 1= 10 hours : Score=70
>>> Hour attending class subject 2= 12 hours : Score=80
>>> .
>>> .
>>> .
>>> .
>>> Student B: Age 25
>>> Hour attending class subject 1= 10 hours : Score 55
>>> Hour attending class subject 2= 20 hours : Score 60
>>> .
>>> .
>>> .
>>> .
>>>
>>> Let plot hour attending class subject (x) vs score (y). Each curve is
>>> colored according to the age to see any trend.
>>
>> Fine.  So let's assume your student's ages run from 20 to 30.
>> Then we have
>>   set cbrange [20:30]
>>   plot 'student1' using ... with lines lc cb 21,
>>        'student2' using ... with lines lc cb 25,
>>                'student3' ...
>> and so on.
>>
>>> In my earliest post, notice linespoints give correct color and symbol
>>> according to the plot/key, just like the curve itself. Only the line
>>> color is wrong.
>>> If the plot can do color palette/gradient on the curve correctly(or
>>> may be incorrectly) why not the key?
>>
>> You have asked it to color the lines by z value.
>> Each point or line segment has a z value.
>> But what is the z value of the key?  It has none.
>>
>>        Ethan
>>
>>
>>> Thanks.
>>>
>>> On Thursday 11 March 2010 23:30:28 hon fui lee wrote:
>>> > I'm trying to do a 2D lines/linespoint plot with linecolor from 3rd
>>> > column as color palette.
>>> > All are OK except the key does not proper linecolor. See sample
>>> > command file and sample output (pdf).
>>> > I'm using gnuplot version 4.5 (development) on Windows.
>>> >
>>> > Is that a bug or feature? Thanks.
>>>
>>> I think it is a mis-expectation.
>>>
>>> Your lines happen to each have a constant Z value, which you can think of
>>> as a color value, so for your particular plot each entire line is a
>>> single color and it would make sense for the sample line segment in the
>>> key to be that same color.
>>>
>>> But how is gnuplot supposed to know this?  In general each point could
>>> have a different Z value and each line would have many segments with
>>> various colors.  Which of these colors would you put in the key?
>>>
>>> If you know in advance that each line has a constant Z value, maybe
>>> you can revise the plot command so that instead of
>>>    plot 'foo' using 1:2:3 lc palette
>>> you use
>>>    Z = constant_z_for_this_line
>>>    plot 'foo' using 1:2 lc palette Z
>>>
>>> For this you would have to read in the Z values before issuing the
>>> plot command.  That may or may not be possible in your particular
>>> plotting scenario.
>>>
>>>       Ethan
>>
>
>
>
> --
> hon_fui
>



-- 
hon_fui