如何在Gnuplot中合并两个图

Question

如何在同一图表中合并箱形图和线图？ 我有两个数据文件。一个用于绘制框图，另一个用于绘制线图。使用这些数据文件，如何在同一图表中绘制框和线图。

提前致谢

set terminal pngcairo size  1024,768 enhanced font "Helvetica,15"
set output "filename"

unset log 
unset label
unset key

set style fill solid 0.0 border -1
set style boxplot outliers pointtype 7
set style data boxplot

set xrange [0 to 30]
set xtics ("0" 1, "5" 2, "10" 3, "15" 4, "20" 5, "25" 6, "27" 7, "29" 8, "30" 9) scale 0.0

set xtics nomirror
set ytics nomirror

set yrange [0 to 150]
set ytics 0,10,150
set title " "
set xlabel " "
set ylabel " "

plot for [i=1:9] 'file1' using (i):i notitle with boxplot lt -1, \
     'file2' with linespoints ls 1 ps 2 lw 2 lt rgb "blue"