Ternary Operator | ||
Symbol | Example | Explanation |
?: |
a?b:c |
ternary operation |
The ternary operator behaves as it does in C. The first argument (a), which must be an integer, is evaluated. If it is true (non-zero), the second argument (b) is evaluated and returned; otherwise the third argument (c) is evaluated and returned.
The ternary operator is very useful both in constructing piecewise functions and in plotting points only when certain conditions are met.
Examples:
Plot a function that is to equal sin(x) for 0 = x
1, 1/x for 1
= x
2,
and undefined elsewhere:
f(x) = 0<=x && x<1 ? sin(x) : 1<=x && x<2 ? 1/x : 1/0 plot f(x)
For data in a file, plot the average of the data in columns 2 and 3 against the datum in column 1, but only if the datum in column 4 is non-negative:
plot 'file' using 1:( $4<0 ? 1/0 : ($2+$3)/2 )
For an explanation of the using syntax, please see plot datafile using (p. ).