在gnuplot函数中使用awk或其他shell命令

时间:2012-10-11 19:03:04

标签: awk gnuplot

我想要这样的事情:

file1='logs/last/mydata1.log'
file2='logs/last/mydata2.log'

# declare function that uses awk to reshape the data - does not work :(
sum1(fname)=("<awk '{sum=0; for(i=8;i<=NF;i+=2) sum+=$i; print $1,sum/2}' $fname")
sum2(fname)=("<awk '{sum=0; for(i=9;i<=NF;i+=2) sum+=$i; print $1,sum/2}' $fname")

# plot different columns of my file and awk processed file
plot file1 u 1:2 title "thing A measure 1" w l, \
     file1 u 3:4 title "thing A measure 2" w l, \
     file2 u 1:2 title "thing B measure 1" w l, \
     file2 u 3:4 title "thing B measure 2" w l, \
     sum1(file1) u 1:2 title "group A measure 1" w l, \
     sum2(file1) u 1:2 title "group A measure 2" w l, \
     sum1(file2) u 1:2 title "group B measure 1" w l, \
     sum2(file2) u 1:2 title "group B measure 2" w l

什么不起作用是在gnuplot函数中有awk的部分。 在awk正常工作后直接使用我的plot脚本:

plot "<awk '{sum=0; for(i=9;i<=NF;i+=2) sum+=$i; print $1,sum}' ./logs/last/mydata1.log" u 1:2 w l

有没有办法将awk或其他shell命令放入gnuplot函数中? 我知道我可以将awk脚本外包给另一个文件并在plot后直接写入该文件,但我不想要单独的文件。

1 个答案:

答案 0 :(得分:23)

$var不会像在shell中那样在gnuplot中的字符串中展开var。您想使用gnuplot的字符串连接(使用.运算符):

sum1(fname)="<awk '{sum=0; for(i=8;i<=NF;i+=2) sum+=$i; print $1,sum/2}' ".fname

或者,如果您觉得更舒服,我想您可以使用sprintf

sum1(fname)=sprintf("<awk '{sum=0; for(i=8;i<=NF;i+=2) sum+=$i; print $1,sum/2}' %s",fname)

*请注意,这实际上并不执行命令。它只构建将传递给plot的字符串,然后plot将执行该命令。如果您确实想在函数中执行命令,可以将system作为函数调用。来自文档:

`system "command"` executes "command" using the standard shell. See `shell`.
 If called as a function, `system("command")` returns the resulting character
 stream from stdout as a string.  One optional trailing newline is ignored.

 This can be used to import external functions into gnuplot scripts:

       f(x) = real(system(sprintf("somecommand %f", x)))