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