Question

Short question:
How do I display the _ (underscore) character in a title in gnuplot that is assigned from a variable name in gnuplot?

Details:
I have something like the following code:

items = "foo_abc foo_bcd bar_def"
do for [item in items] {
  set title item
  set output item.eps
  plot item."-input.txt" using 1:2 title item with linespoints
}

This works fine with gnuplot except that the title get changed from foo_abc to foo_abc. I don’t know if I want to use an escape character because I don’t want that to be in the file name. I’ve tried a couple of different options with single vs. double quotes but I haven’t found what I need yet.

Answer 1

If you are using the enhanced eps terminal, that is the reason you need to escape the underscore in the first place. There was another related question today which explains the issue a bit. When you set the terminal, try:

set terminal postscript noenhanced <whatever else here...>

That works for me (Arch linux, gnuplot 4.7.0). If the enhanced terminal is essential, below is a partial solution I found. The assumption is that the underscore always appears in the same place in the string.

set terminal postscript enhanced
items = 'foo\_abc foo\_bcd bar\_def'
do for [item in items] {
  set output item[1:3].item[5:*].'.eps'
  set title item
  plot sin(x)
}

This way you can escape the underscore and not have the \ appear in the filename. Note the use of single quotes for the ‘items’ string; see the previously linked question for details.