Kdtyjb

I have created with matlab2tikz a standalone picture, saved in myfile.tikz

Here is the code:

  % This file was created by matlab2tikz v0.5.0 running on MATLAB 8.4.

%Copyright (c) 2008--2014, Nico Schlömer <nico.schloemer@gmail.com>

%All rights reserved.

%Minimal pgfplots version: 1.3

%

%The latest updates can be retrieved from

%  http://www.mathworks.com/matlabcentral/fileexchange/22022-matlab2tikz

%where you can also make suggestions and rate matlab2tikz.

%

documentclass[tikz]{standalone}

usepackage{pgfplots}

usepackage{grffile}

pgfplotsset{compat=newest}

usetikzlibrary{plotmarks}

usepackage{amsmath}



begin{document}

begin{tikzpicture}



begin{axis}[%

width=5.828221in,

height=4.83871in,

  y tick label style={

        /pgf/number format/.cd,

            fixed,

            precision=2,

        /tikz/.cd

    },

at={(0in,0in)},

xlabel={Amount of trajectories $(times 10^7 )$},

ylabel={4th largest eigenvalue},

scale only axis,

separate axis lines,

every outer x axis line/.append style={white!15!black},

every x tick label/.append style={font=color{white!15!black}},

xmin=10,

xmax=50,

every outer y axis line/.append style={white!15!black},

every y tick label/.append style={font=color{white!15!black}},

ymin=0,

ymax=0.4,

legend style={draw=white!15!black,legend cell align=left}

]

addplot [color=red,solid,mark=square*,mark options={solid,fill=red}]

  table[row sep=crcr]{%

10  0.263363834999385\

11  0.267956137706241\

12  0.234749040704818\

13  0.179095397783884\

14  0.15598488764853\

15  0.107130784874058\

16  0.102335812851717\

17  0.15130873420001\

18  0.13294322038256\

19  0.0960614078900675\

20  0.0668875403805097\

21  0.0696202544023205\

22  0.0769402122493772\

23  0.0814760237222062\

24  0.0697776185374109\

25  0.0890537892164226\

26  0.0966623314755249\

27  0.0934599345653749\

28  0.0878880498733259\

29  0.087473866000113\

30  0.0892704892496597\

31  0.0812007102089455\

32  0.0785448212326198\

33  0.0772843849145571\

34  0.0748381690948553\

35  0.076911866585151\

36  0.0690916321763139\

37  0.0681618703751155\

38  0.0538871718086814\

39  0.0462813570913469\

40  0.042327952187128\

41  0.0545656572749185\

42  0.0502509655943423\

43  0.0548481613029811\

44  0.0565260239184772\

45  0.0574958892089851\

46  0.0565141460485921\

47  0.0607219533955611\

48  0.0621210992930102\

49  0.0584171708241252\

50  0.0554092144619335\

};

addlegendentry{Standart estimation};



addplot [color=blue,dash pattern=on 1pt off 3pt on 3pt off 3pt,mark=asterisk,mark options={solid}]

  table[row sep=crcr]{%

10  0.357550039744943\

11  0.356972039378709\

12  0.334368502350565\

13  0.30613803777209\

14  0.298223941905334\

15  0.343030324802327\

16  0.344206127225485\

17  0.342654565258385\

18  0.26909949152418\

19  0.244071723963408\

20  0.242341053266382\

21  0.242231681701872\

22  0.23431468104395\

23  0.234032984140502\

24  0.225001418677598\

25  0.187193611177314\

26  0.195346678096106\

27  0.194987732958593\

28  0.193281499543124\

29  0.193039372776092\

30  0.188745282175345\

31  0.18389991087615\

32  0.184250604858391\

33  0.18358622178072\

34  0.183425365322753\

35  0.183581339448476\

36  0.169460638908507\

37  0.166155309985801\

38  0.160320243705676\

39  0.14731116222724\

40  0.144469472179117\

41  0.143751331186272\

42  0.143538751559955\

43  0.142526804916181\

44  0.142099807792203\

45  0.142164474247563\

46  0.137436117746078\

47  0.13816942742473\

48  0.137543995531934\

49  0.137932768120272\

50  0.137592136659409\

};

addlegendentry{Corrected Frobenius estimation};



end{axis}

end{tikzpicture}%

end{document}

In my terminal, I can produce a pdf file of my picture by entering

pdflatex myfile.tikz

This is how it looks:

I want to produce a PDF file only containing the legend of the pgfplot. Is this possible?

Edit: I would like to have this outcome:

Whereas LaRiFaRi's solution provides this:

How can I get the first picture? Do I need to trial-and-error or is there a shorter version for it? Removing xmax, ymax, xmin and ymin produced an empty image.

I do not know, why we need xmin, xmax, ... here, but well, it works (at least I hope this is what you have wanted):

% arara: pdflatex



documentclass{standalone}

usepackage{pgfplots}

pgfplotsset{compat=1.12}



begin{document}

begin{tikzpicture} 

    begin{axis}[%

    hide axis,

    xmin=10,

    xmax=50,

    ymin=0,

    ymax=0.4,

    legend style={draw=white!15!black,legend cell align=left}

    ]

    addlegendimage{red,mark=square*}

    addlegendentry{Standart estimation};

    addlegendimage{blue,dash pattern=on 1pt off 3pt on 3pt off 3pt,mark=asterisk,mark options={solid}}

    addlegendentry{Corrected Frobenius estimation};

    end{axis}

end{tikzpicture}

end{document}

NB: Try to use the compat parameter with your actual version.