documentclass{article}
usepackage{pgfplots}
pgfplotsset{compat=newest}
usepgfplotslibrary{groupplots}


newcommand{datapthreeone}{prob3.dat}
begin{filecontents*}{datapthreeone}
    x1     y1  averX  averY     Ex     Ey
 2.000,  3.000, -0.714,  1.000,  1.000, -0.714
 1.000,  2.000, -1.714,  0.000,  0.000, -1.714
 1.000,  1.000, -1.714, -1.000, -1.000, -1.714
 2.000,  2.000, -0.714,  0.000,  0.000, -0.714
 4.000,  2.000,  1.286,  0.000,  0.000,  1.286
 4.000,  3.000,  1.286,  1.000,  1.000,  1.286
 5.000,  1.000,  2.286, -1.000, -1.000,  2.286
end{filecontents*}

begin{document}
begin{figure}
begin{center}
begin{tikzpicture}
begin{groupplot}[group style={group size=2 by 2, horizontal sep=4em, vertical sep=5em}]
nextgroupplot[xmin=-2, xmax=2, ymin=-2.5, ymax=2.5, legend style={font=fontsize{7}{9}selectfont}, title = (c) PCA Projection Points]
addplot [only marks, line width = 0.3mm, mark=x, blue, mark options={scale=1.2}]table[x index=4, y index=5, only marks,col sep=comma] {datapthreeone}; addlegendentry{emph{Projected Data}}
addplot [-latex, dashed, blue, domain=-2:2, samples=2]{0*x + 0};
addplot[-latex, dashed]coordinates {(-3,0) (2.5,0)};
addplot[-latex, dashed]coordinates {(0,-2.5) (0,2.5)};

nextgroupplot[xmin=-2, xmax=2, ymin=-2.5, ymax=2.5, legend style={font=fontsize{7}{9}selectfont}, title = (c) PCA Projection Points]
addplot [only marks, line width = 0.3mm, mark=x, blue, mark options={scale=1.2}]table[x index=4, y index=5, only marks,col sep=comma] {datapthreeone}; addlegendentry{emph{Projected Data}}
addplot [-latex, dashed, blue, domain=-2:2, samples=2]{0*x + 0};
addplot[-latex, dashed]coordinates {(-3,0) (2.5,0)};
addplot[-latex, dashed]coordinates {(0,-2.5) (0,2.5)};

end{groupplot}

end{tikzpicture}
end{center}
end{figure}

end{document}