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How to define colour name by string to use in linecolour lc, not working gnuplot

The following code does not produce any error but it just ouptut a grey line,

col2="#cd0000"
p x w l lc col2

while this one gives a red line as it should

p x w l lc "#cd0000"

Is this a bug?

Solution

  • Check help colorspec. You can also insert rgb. This will also give a red line.

    col2 = "#cd0000"
plot x w l lc rgb col2

    From help colorspec:

    Syntax:

      ... {linecolor | lc} {"colorname" | <colorspec> | <n>}

    where <colorspec> has one of the following forms:

      rgbcolor "colorname"    # e.g. "blue"
  rgbcolor "0xRRGGBB"     # string containing hexadecimal constant
  rgbcolor "0xAARRGGBB"   # string containing hexadecimal constant
  rgbcolor "#RRGGBB"      # string containing hexadecimal in x11 format
  rgbcolor "#AARRGGBB"    # string containing hexadecimal in x11 format
  rgbcolor <integer val>  # integer value representing AARRGGBB
  rgbcolor variable       # integer value is read from input file
    • "#cd0000" is not a valid color name, like "red", "green", "blue"
    • "#cd0000" is not a valid colorspec
    • "#cd0000" is a string which cannot be interpreted as a number, then it looks like gnuplot will take 0, which is black.