3.2.6. - Modes 4 & 5: Break lines around points
This mode is useful if the current data is a dense set of points to be drawn as a line and you wish to break the line around a sparser set of points drawn as discrete symbols. This may be the case, for instance, when you draw a fitted or theoretical curve through data.
Assume, for example, that you have drawn the axes and data points from datafile, and the current data is to be the smooth curve, perhaps generated from a user function (see Chapter 11). If you type
gd 4 datafilepoints "near" the sparse data points of datafile won't be drawn when a point-drawing command such as
pp is executed
with a line symbol, as in the following example.
The actual distance used to define a nearby point is proportional to the character size of the symbol (see
cs, Chapter 6).
To
increase the gap around the symbols, increase the size of the symbol
width before entering
gd 4.
If the error-bar mode is on when
the points are read, the line also will be broken about the error
bars.
This mode does not interpolate between points. You must have a large number of points for the breaks in the line to be symmetric.
Mode 5 is the same as 4, except that you specify columns for x, y and, optionally, r and s.
These modes work by assigning line-control information to each point. However, the user-toggled line-control mode is turned off. Although the data will be drawn using the line-control information, that information will not be used by other commands such as
sa or
gd 7
.
If you do turn line-control mode on (or back on) with the
lc command, the line-control information obtained from modes 4 or 5 will
be available for other commands.
Note that the symbol filling available on many filters can be used to produce a similar effect by drawing open symbols over solid lines.