Sorry if this doesn't seem well-researched, but I couldn't find the answer anywhere.

Is there a way to reverse an axis in a TikZ datavisualization? Concretely, I want to reverse the y axis in a cartesian system, so that positive points down.

From what I've gathered from this question, when manually specifying an axis you can use the key y dir=reverse. But I haven't found any equivalent way using the datavisualization library. I'm using the school book axes system.

Here's what I've tried:

datavisualization [school book axes,

                    y dir=reverse]

datavisualization [school book axes,

                    all axes={y dir=reverse}]

datavisualization [school book axes,

                    y axis=reverse]

datavisualization [school book axes,

                    y={dir=reverse}]

MWE

This is what I'm working on. I've stripped down the preamble to a minimum.

documentclass[11pt, a4paper]{article}

usepackage[margin=2.5cm]{geometry}

usepackage{tikz}

usetikzlibrary{datavisualization}



usepackage{filecontents}

begin{filecontents}{1.csv}

0, 0

0.100000, -0.102985

0.200000, -0.284078

0.300000, -0.431294

0.800000, -0.886640

0.900000, -0.946767

1.000000, -1.000000

end{filecontents}



begin{filecontents}{2.csv}

0, 0

0.104298, -0.280000

0.213643, -0.440000

0.300496, -0.540000

0.709127, -0.860000

0.820097, -0.920000

0.904455, -0.960000

1.000000, -1.000000

end{filecontents}



begin{filecontents}{3.csv}

0, 0

0.105170, -0.292368

0.205373, -0.440170

0.325606, -0.575855

0.435812, -0.676699

0.502248, -0.729587

0.663074, -0.838455

0.760352, -0.893359

0.871594, -0.947572

1.000000, -1.000000

end{filecontents}





begin{document}



    begin{tikzpicture}[>=stealth]

    datavisualization data group {methods} = {

        data [set=m1, read from file={1.csv}]

        data [set=m2, read from file={2.csv}]

        data [set=m3, read from file={3.csv}]

    };



    datavisualization [school book axes,

                        visualize as scatter/.list={m1,m3,m2},

                        all axes={unit length=8cm},

                        x axis={label=$x$},

                        y axis={label=$y$},

                        style sheet={vary hue},

                        style sheet={cross marks},

                        data/headline={x,y}]



        data group {methods};

    end{tikzpicture}

end{document}

The complete CSV files can be found here.

Current output

What I'm aiming for

Something like this:

begin{tikzpicture}[>=stealth, scale=6]

        coordinate (X) at (1.3, 0);

        coordinate (Y) at (0, -1.1);

        draw[black!30, very thin] (X) grid (Y);

        draw[black!5, very thin, step=0.2] (X) grid (Y);



        draw[->, very thick]  (0, 0) -- node[very near end, anchor=south west] {Large$x$} (X);

        draw[->, very thick]  (0, 0) -- node[very near end, anchor=north east] {Large$y$} (Y);



        draw[blue, loosely dotted, very thick] plot file {1.data};

        draw[purple, loosely dotted, ultra thick] plot file {2.data};

        draw[red, loosely dotted, very thick] plot file {3.data};

end{tikzpicture}

Here 1.data, 2.data and 3.data are exactly like the CSV files but separated by spaces instead of commas.

Thanks for updating your question!

I do not have much experience with data visualization. The only thing I can offer is a pgfplots version of your graph. There sign flip can be achieved simply by adding the key y dir=reverse.

documentclass[11pt, a4paper]{article}

usepackage[margin=2.5cm]{geometry}

usepackage{pgfplots}

pgfplotsset{compat=1.16}



usepackage{filecontents}

begin{filecontents*}{1.csv}

0, 0

0.020000, -0.000347

0.040000, -0.009989

0.060000, -0.033917

0.080000, -0.066399

0.100000, -0.102985

0.120000, -0.140917

0.140000, -0.178608

0.160000, -0.215232

0.180000, -0.250425

0.200000, -0.284078

0.220000, -0.316210

0.240000, -0.346897

0.260000, -0.376240

0.280000, -0.404339

0.300000, -0.431294

0.320000, -0.457194

0.340000, -0.482119

0.780000, -0.873711

0.800000, -0.886640

0.820000, -0.899258

0.840000, -0.911571

0.860000, -0.923589

0.880000, -0.935319

0.900000, -0.946767

0.920000, -0.957940

0.940000, -0.968844

0.960000, -0.979485

0.980000, -0.989869

1.000000, -1.000000

end{filecontents*}



begin{filecontents*}{2.csv}

0, 0

0.002644, -0.020000

0.006417, -0.040000

0.011080, -0.060000

0.016513, -0.080000

0.022645, -0.100000

0.029425, -0.120000

0.036820, -0.140000

0.044804, -0.160000

0.053358, -0.180000

0.062468, -0.200000

0.072123, -0.220000

0.082316, -0.240000

0.093042, -0.260000

0.104298, -0.280000

0.116083, -0.300000

0.128398, -0.320000

0.141246, -0.340000

0.154629, -0.360000

0.168553, -0.380000

0.183024, -0.400000

0.198051, -0.420000

0.213643, -0.440000

0.229810, -0.460000

0.246564, -0.480000

0.263919, -0.500000

0.281891, -0.520000

0.300496, -0.540000

0.643284, -0.820000

0.675487, -0.840000

0.709127, -0.860000

0.744333, -0.880000

0.781261, -0.900000

0.820097, -0.920000

0.861068, -0.940000

0.904455, -0.960000

0.950612, -0.980000

1.000000, -1.000000

end{filecontents*}



begin{filecontents*}{3.csv}

0, 0

0.007957, -0.055479

0.010327, -0.065792

0.013265, -0.077471

0.016876, -0.090623

0.021278, -0.105355

0.026607, -0.121775

0.033015, -0.139989

0.040673, -0.160100

0.049771, -0.182208

0.060520, -0.206407

0.073158, -0.232783

0.087945, -0.261415

0.105170, -0.292368

0.125154, -0.325696

0.148248, -0.361432

0.174844, -0.399593

0.205373, -0.440170

0.280191, -0.528391

0.325606, -0.575855

0.377226, -0.625362

0.435812, -0.676699

0.502248, -0.729587

0.577578, -0.783662

0.663074, -0.838455

0.760352, -0.893359

0.871594, -0.947572

1.000000, -1.000000

end{filecontents*}





begin{document}



begin{tikzpicture}

  begin{axis}[axis lines=middle,xlabel=$x$,ylabel=$y$,y dir=reverse,

    y axis line style={stealth-},xtick=empty,ytick=empty,enlargelimits=0.1]

    addplot+[only marks] table[header=false,x index=0,y index=1,col sep=comma] {1.csv};

    addplot+[only marks] table[header=false,x index=0,y index=1,col sep=comma] {2.csv};

    addplot+[only marks] table[header=false,x index=0,y index=1,col sep=comma] {3.csv};

  end{axis}

end{tikzpicture}

end{document}

Ok, this was a little tricky, but I was able to figure it out with data visualization. The approach scales the y-axis by -1 (as mentioned in my comment). As you mentioned, however, this also flips the axis values and not only the data.

Approach #1:

Perhaps this is not the most elegant approach, but you can forcibly "re-calculate" the y-value tick labels with:

defreverseyaxis#1{%

    pgfmathparse{#1*-1}%

    pgfmathprintnumber{pgfmathresult}%

}

And then update the ticks values within datavisualization parameters:

tick typesetter/.code=reverseyaxis{##1}

Here is a complete version, which I put into @marmot's answer above (except for the color coding):

% ---DOCUMENT CLASS---

documentclass[11pt, a4paper]{article}

usepackage[margin=2.5cm]{geometry}



% ---MISC. PACKAGES---

usepackage{pgfplots}



% ---TIKZ---

usepackage{tikz}

usetikzlibrary{datavisualization}



% ---PLOTS---

pgfplotsset{compat=1.16}



usepackage{filecontents}

begin{filecontents*}{1.csv}

0, 0

0.020000, -0.000347

0.040000, -0.009989

0.060000, -0.033917

0.080000, -0.066399

0.100000, -0.102985

0.120000, -0.140917

0.140000, -0.178608

0.160000, -0.215232

0.180000, -0.250425

0.200000, -0.284078

0.220000, -0.316210

0.240000, -0.346897

0.260000, -0.376240

0.280000, -0.404339

0.300000, -0.431294

0.320000, -0.457194

0.340000, -0.482119

0.780000, -0.873711

0.800000, -0.886640

0.820000, -0.899258

0.840000, -0.911571

0.860000, -0.923589

0.880000, -0.935319

0.900000, -0.946767

0.920000, -0.957940

0.940000, -0.968844

0.960000, -0.979485

0.980000, -0.989869

1.000000, -1.000000

end{filecontents*}



begin{filecontents*}{2.csv}

0, 0

0.002644, -0.020000

0.006417, -0.040000

0.011080, -0.060000

0.016513, -0.080000

0.022645, -0.100000

0.029425, -0.120000

0.036820, -0.140000

0.044804, -0.160000

0.053358, -0.180000

0.062468, -0.200000

0.072123, -0.220000

0.082316, -0.240000

0.093042, -0.260000

0.104298, -0.280000

0.116083, -0.300000

0.128398, -0.320000

0.141246, -0.340000

0.154629, -0.360000

0.168553, -0.380000

0.183024, -0.400000

0.198051, -0.420000

0.213643, -0.440000

0.229810, -0.460000

0.246564, -0.480000

0.263919, -0.500000

0.281891, -0.520000

0.300496, -0.540000

0.643284, -0.820000

0.675487, -0.840000

0.709127, -0.860000

0.744333, -0.880000

0.781261, -0.900000

0.820097, -0.920000

0.861068, -0.940000

0.904455, -0.960000

0.950612, -0.980000

1.000000, -1.000000

end{filecontents*}



begin{filecontents*}{3.csv}

0, 0

0.007957, -0.055479

0.010327, -0.065792

0.013265, -0.077471

0.016876, -0.090623

0.021278, -0.105355

0.026607, -0.121775

0.033015, -0.139989

0.040673, -0.160100

0.049771, -0.182208

0.060520, -0.206407

0.073158, -0.232783

0.087945, -0.261415

0.105170, -0.292368

0.125154, -0.325696

0.148248, -0.361432

0.174844, -0.399593

0.205373, -0.440170

0.280191, -0.528391

0.325606, -0.575855

0.377226, -0.625362

0.435812, -0.676699

0.502248, -0.729587

0.577578, -0.783662

0.663074, -0.838455

0.760352, -0.893359

0.871594, -0.947572

1.000000, -1.000000

end{filecontents*}





defreverseyaxis#1{%

    pgfmathparse{#1*-1}%

    pgfmathprintnumber{pgfmathresult}%

}



begin{document}



begin{tikzpicture}

        datavisualization [school book axes,

                            all axes={length=6cm},

                            x axis={min value=0,max value=1,ticks={step=0.5,minor steps between steps=4}},

                            y axis={min value=-1,max value=1,ticks={step=0.5,minor steps between steps=4,tick typesetter/.code=reverseyaxis{##1}}},

                            yscale=-1,

                                visualize as scatter]%



            data[headline={x, y}, read from file={1.csv}]

            data[headline={x, y}, read from file={2.csv}]

            data[headline={x, y}, read from file={3.csv}]

        ;

end{tikzpicture}



end{document}

You'll notice that the axis arrow is now pointing down. The axes visualizations are customizable, but I do not know exactly what you need...so I left it this way for now.

Approach #2: (image is the same as approach #1)

I found a slightly different way that doesn't require a new command and re-calculating the y-axis ticks. It's not automatic, however, and requires using the same length from all axes={length=6cm} (in my example). You need these three options in datavisualization:

• all axes={length=6cm}




• yscale=-1




• y axis={min value=-1,max value=1,ticks={step=0.5,minor steps between
steps=4,rotate=180,yshift=-6cm}}

Same code as above, but here is the tikzpicture code for version #2:

begin{tikzpicture}

        datavisualization [school book axes,

                            all axes={length=6cm},

                            x axis={min value=0,max value=1,ticks={step=0.5,minor steps between steps=4}},

                            yscale=-1,

                            y axis={min value=-1,max value=1,ticks={step=0.5,minor steps between steps=4,rotate=180,yshift=-6cm}},

                                visualize as scatter]%



            data[headline={x, y}, read from file={1.csv}]

            data[headline={x, y}, read from file={2.csv}]

            data[headline={x, y}, read from file={3.csv}]

        ;

end{tikzpicture}

The approach takes advantage of simply rotating the y-axis 180 degrees. The problem is that the pivot point is not as 0, but at the maximum value on the y-axis. Therefore, you need to shift it downwards by the length of the y-axis.