My table is too big and won't fit a page, so I wanted it to be a little smaller. Maybe reduce spaces between each column and draw a line instead.
Adding
column type/.add={|}{}% results in '|c'
put the vertical lines and the table looked better, but it's still too big.
Here's the code, there are more data to it, but I removed some so the code wouldn't be huge:
\documentclass{article}
\usepackage{booktabs}
\usepackage{pgfplotstable}
%\usepackage[paperwidth=35cm]{geometry}
\begin{document}
\pgfplotstabletypeset[
every head row/.style={
before row={\toprule
& &
&\multicolumn{2}{c}{32-2}
&\multicolumn{2}{c}{128-4}
&\multicolumn{2}{c}{256-8}\\
},
after row=\midrule
},
display columns/0/.style={column name={Instance}},
display columns/1/.style={column name={n}},
display columns/2/.style={column name={m}},
display columns/3/.style={column name={Avg. Time.}},
display columns/4/.style={column name={Avg. Qual.}},
display columns/5/.style={column name={Avg. Time.}},
display columns/6/.style={column name={Avg. Qual}},
display columns/7/.style={column name={Avg. Time.}},
display columns/8/.style={column name={Avg. Qual.}},
every last row/.style={after row=\bottomrule},
string type,
header=false
]
{
hp1.dat 28 4 3.7960 0.9763 5.8166 0.9850 8.0020 0.9895
hp2.dat 35 4 4.0924 0.9673 6.8730 0.9696 9.9091 0.9717
pb1.dat 27 4 3.4976 0.9843 5.2666 0.9890 7.5312 0.9947
pb2.dat 34 4 4.1574 0.9730 7.3916 0.9783 10.5208 0.9812
pb4.dat 29 2 2.9995 0.9996 4.3949 1.0000 6.1613 1.0000
pb5.dat 20 10 2.7515 0.9782 3.6325 0.9820 4.9027 0.9868
pb6.dat 40 30 3.7279 0.9088 5.2931 0.9034 7.5250 0.9093
pb7.dat 37 30 5.9737 0.9894 9.8045 0.9833 14.3086 0.9865
}
\end{document}
Result:


