Gdtyjr

Problem

When changing the values of the markers on a scatter plot using the visualization depends on key and when the data comes from a pgfplotstable the marker printing is broken.

If I have the table data explicitly on the addplot it works (see example 3). Similarly, if I have the data coming from a pgfplotstable and without the visualization handler, it also works (see example 1).

However, if I mix both, it just stops printing the markers (see example 2).

Question

How can I make the visualization depends on=value and data coming from a pgfplotstable work together?

Examples

documentclass[convert]standalone
usepackagepgfplots, pgfplotstable
begindocument

pgfdeclareplotmarkapgfuseplotmark*
pgfdeclareplotmarkbpgfuseplotmarktriangle*
pgfdeclareplotmarkcpgfuseplotmarksquare*

pgfplotstableread%
x y label
0.1 0.15 a
0.45 0.27 c
0.02 0.17 a
0.06 0.1 a
0.9 0.5 b
0.5 0.3 c
0.85 0.52 b
0.12 0.05 a
0.73 0.45 b
0.53 0.25 c
0.76 0.5 b
0.55 0.32 c
tab

begintikzpicture
beginaxis[legend pos=south east]
 addplot[%
 scatter,
 only marks,
% visualization depends on=value thisrowlabelaslabel,
% scatter/@pre marker code/.append style=/tikz/mark=label,
 ]
 table[x=x,y=y]tab;
 legendClass 1,Class 2,Class 3
endaxis
endtikzpicture
begintikzpicture
beginaxis[legend pos=south east]
 addplot[%
 scatter,
 only marks,
 visualization depends on=value thisrowlabelaslabel,
 scatter/@pre marker code/.append style=/tikz/mark=label,
 ]
 table[x=x,y=y]tab;
 legendClass 1,Class 2,Class 3
 endaxis
endtikzpicture
begintikzpicture
beginaxis[legend pos=south east]
 addplot[%
 scatter,
 only marks,
 visualization depends on=value thisrowlabelaslabel,
 scatter/@pre marker code/.append style=/tikz/mark=label,
 ]
 table[x=x,y=y]
 x y label
 0.1 0.15 a
 0.45 0.27 c
 0.02 0.17 a
 0.06 0.1 a
 0.9 0.5 b
 0.5 0.3 c
 0.85 0.52 b
 0.12 0.05 a
 0.73 0.45 b
 0.53 0.25 c
 0.76 0.5 b
 0.55 0.32 c
 ;
 legendClass 1,Class 2,Class 3
endaxis
endtikzpicture
enddocument

More Context

I'm trying to create some columns from a table, and then trying to plot it. Hence, my need to use a pgfplotstable as the source of the data.

I can change the size of the marker using @pre marker code/.append code handler. However, the @pre marker code/.append style also gives error (not sure if that is related to this problem though).

So, in some sense, I can see that the @pre marker code is seeing the values created with the visualization depends on definition. But for some particular reason it doesn't sees this one with non-numerical values.

Any ideas or hints why this may be happening?