Syntax:
set datafile missing {"<string>"} show datafile missing unset datafile
Example:
# Ignore entries containing IEEE NaN ("Not a Number") code set datafile missing "NaN"
Example:
set datafile missing "?" set style data lines plot '-' 1 10 2 20 3 ? 4 40 5 50 e plot '-' using 1:2 1 10 2 20 3 ? 4 40 5 50 e plot '-' using 1:($2) 1 10 2 20 3 ? 4 40 5 50 e
The first plot will recognize only the first datum in the "3 ?" line. It will use the single-datum-on-a-line convention that the line number is "x" and the datum is "y", so the point will be plotted (in this case erroneously) at (2,3).
The second plot will correctly ignore the middle line. The plotted line will connect the points at (2,20) and (4,40).
The third plot will also correctly ignore the middle line, but the plotted line will not connect the points at (2,20) and (4,40).
There is no default character for missing, but in many cases any non-parsible string of characters found where a numerical value is expected will be treated as missing data.