Styles in datavisualization legends

Question

I have a bunch of plots in a datavisualization environment with different styles for each plot. When I collect them into a legend, they all show up in black. I've constructed a quick MWE based on an example in the manual

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{datavisualization}

\begin{document}
\begin{tikzpicture}
  \datavisualization data group {lines} = {
   data point [x=0, y=0, set=normal]
data point [x=2, y=2, set=normal]
data point [x=0, y=1, set=heated]
data point [x=2, y=1, set=heated]
data point [x=0.5, y=1.5, set=critical]
data point [x=2.25, y=1.75, set=critical]
                                };
  \datavisualization [
school book axes={unit=0.3},
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
normal={style={green}, label in legend={text={normal}}},
heated={style={yellow}, label in legend={text={heated}}},
critical={style={red}, label in legend={text={critical}}},
legend=north east inside]
  data group {lines};
\end{tikzpicture}
\end{document}

Do I need to specify the colour information somewhere again? When using style sheets, the colours show up correctly in the legend but I would greatly prefer to set colours separately.

are you sure? Because, when I compiled your MWE, it works as you wanted. I see no problems. — Raaja_is_at_topanswers.xyz, Aug 02 '18 at 14:07
Strange, I get the behaviour shown in the image. Can you tell me your TeX version? — Huang_d, Aug 02 '18 at 14:09
MiKTex-2.9.6300 compiled with Texstudio 2.11.2. I hope that helps. — Raaja_is_at_topanswers.xyz, Aug 02 '18 at 14:12
I confirm @RaajaG's statement with my TeXLive 2018 distribution. Wait! I do get the OP's output when compiling with xelatex, but with pdflatex and lualatex the colors show correctly. (I do not know if that is related, but it also happens with pstricks that xelatex sometimes fails to produce the correct result.) — , Aug 02 '18 at 14:13
I have TeXLive 2018 as well, Live Utility shows no available updates for tikz. Strange… Are there any other ways to set the colour of the legend labels? — Huang_d, Aug 02 '18 at 14:15
@RaajaG Yes, that is in agreement with my findings: only xelatex fails to produce the correct output. Could you please try xelatex? — , Aug 02 '18 at 14:18
Latex, Xelatex, Xetex all produce the same output for me, whether this is changed in the settings panel of Texlive or in the edit window. — Huang_d, Aug 02 '18 at 14:20
A restart of the Texshop editor changed it. Still strange behaviour under Xelatex. Is this a bug I should file? The prior setting was on Xelatex. — Huang_d, Aug 02 '18 at 14:20
@RaajaG Just to be absolutely certain: when you compile with xelatex, the legend curves are colored and not black (as in the OP's screen shot)? — , Aug 02 '18 at 14:24
@marmot for me xelatex does not produces the same output (I agree with you) --> sorry refersh issues --> legends are in BW. — Raaja_is_at_topanswers.xyz, Aug 02 '18 at 14:27
Interestingly, if you add style sheet=vary hue, then some colors show even when compiled with xelatex, but these colors do not match. However, these colors do match when compiled with pdflatex. ... — , Aug 02 '18 at 14:32
After running a few tests with restarting TeXShop: All settings changed in the "Preferences" -> "Typesetting" -> "Default command" panel. XeLaTeX produces black labels. LaTeX produces the correct output. Using style sheet does work, but I prefer having my own colours (for consistency across several graphs) and using XeLaTeX for typesetting. — Huang_d, Aug 02 '18 at 14:35

score 3 · Accepted Answer · 2018-08-02T15:18:27.100

As a workaround, you could create a style sheet that uses the same colors as your lines. Then also xelatex creates a colorful legend.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{datavisualization}

\pgfdvdeclarestylesheet{Huang d}{
  1/.style={green!50!black},
  2/.style={yellow!90!black},
  3/.style={red!80!black},
  default style/.style={black}
}

\begin{document}
\begin{tikzpicture}
  \datavisualization data group {lines} = {
   data point [x=0, y=0, set=normal]
data point [x=2, y=2, set=normal]
data point [x=0, y=1, set=heated]
data point [x=2, y=1, set=heated]
data point [x=0.5, y=1.5, set=critical]
data point [x=2.25, y=1.75, set=critical]
                                };
  \datavisualization [
school book axes={unit=0.3},style sheet=Huang d,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
normal={style={green}, label in legend={text={normal}}},
heated={style={yellow}, label in legend={text={heated}}},
critical={style={red}, label in legend={text={critical}}},
legend=north east inside]
  data group {lines};
\end{tikzpicture}
\end{document}

A much simpler possibility is provided by Huang_d's answer, which can be further simplified to

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{datavisualization}

\pgfdvdeclarestylesheet{xelatex workaround}{
  default style/.style={black}
}

\begin{document}
\begin{tikzpicture}
  \datavisualization data group {lines} = {
   data point [x=0, y=0, set=normal]
data point [x=2, y=2, set=normal]
data point [x=0, y=1, set=heated]
data point [x=2, y=1, set=heated]
data point [x=0.5, y=1.5, set=critical]
data point [x=2.25, y=1.75, set=critical]
                                };
  \datavisualization [
school book axes={unit=0.3},style sheet=xelatex workaround,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
normal={style={green}, label in legend={text={normal}}},
heated={style={yellow}, label in legend={text={heated}}},
critical={style={red}, label in legend={text={critical}}},
legend=north east inside]
  data group {lines};
\end{tikzpicture}
\end{document}

This gives a universal output, i.e. same for pdflatex, xelatex and lualatex.

You are a wonderful marmot! Thank you very much! I guess I will have to take care of the order of plots now, but at least it works with all constraints. — Huang_d, Aug 02 '18 at 14:48
@Huang_d Thanks, yes, that's just a workaround. There seems also an issue with xelatex in pstricks, see e.g. here. To the best of my knowledge, this has never been resolved. And I do not know if these issues are related, let alone how to fix them. But I am glad to hear that this workaround works for you. ;-) — , Aug 02 '18 at 14:54
Playing around with it, you actually still need the normal={style={green}} part, otherwise it is still black. This is some really funky cross-interaction. Setting the style sheet to all black and defining colours in the styles gives the/a desired behaviour, black text and correctly coloured lines. — Huang_d, Aug 02 '18 at 14:59
@Huang_d I confirm your observation and am wondering if you want to post this better workaround as an answer. — , Aug 02 '18 at 15:02

Huang_d · Answer 2 · 2018-08-02T15:37:27.700

The problem seems to be an interaction between Xe(La)TeX and TikZ. In order to get black text with correctly coloured labels, a black style sheet needs to be used. The colours can then be set as expected:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{datavisualization}

\pgfdvdeclarestylesheet{allblack}{default style/.style={black}}

\begin{document}
\begin{tikzpicture}
  \datavisualization data group {lines} = {
   data point [x=0, y=0, set=normal]
data point [x=2, y=2, set=normal]
data point [x=0, y=1, set=heated]
data point [x=2, y=1, set=heated]
data point [x=0.5, y=1.5, set=critical]
data point [x=2.25, y=1.75, set=critical]
                                };
  \datavisualization [
school book axes={unit=0.3},style sheet=allblack,
visualize as line=normal,
visualize as line=heated,
visualize as line=critical,
normal={style={green}, label in legend={text={normal}}},
heated={style={yellow}, label in legend={text={heated}}},
critical={style={red}, label in legend={text={critical}}},
legend=north east inside]
  data group {lines};
\end{tikzpicture}
\end{document}

This yields correctly coloured lines and black text. The text colour can be changed with the style sheet if necessary.

You can do it even shorter: \pgfdvdeclarestylesheet{Huang d}{ default style/.style={black} }. — , Aug 02 '18 at 15:13
I guess you want to either name the style allblack or use style sheet=Huang d in the plot. (I also appended that to my answer, of course giving credit to your answer.) — , Aug 02 '18 at 15:20

Styles in datavisualization legends

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