line2arrow.m

Combines line plotting with annotation arrows.

line2arrow.m Documentation

This line2arrow.m function adds annotation arrows to the end of a line in a 2D Matlab plot. Annotation arrows (created via the Matlab function annotation('arrow', x, y)) are positioned relative to figure coordinates, which can make them difficult to position correctly in terms of axis coordinates. This function does the figure-to-axes coordinate conversion for you.

Arrows inherit line properties from the line they are attached to, unless otherwise specified by the user. You can also resync the line and arrow by clicking on the line. Resyncing matches the arrow color, line width, and line style of the arrows to the lines, and repositions the arrows (because annotation arrows use figure units rather than axis units, the match between the arrow location and line location will be thrown off during some resizing of figures/axes, for example with manual aspect ratios).

Passing a line handle that is already associated with arrows provides the same syncing action as clicking on the line, but can also be used to manually change some properties. See example for details.

Syntax

line2arrow(h);
line2arrow(h, param1, val1, ...)
ha = line2arrow(...)

See function help for description of input and output variables.

Examples

Add an arrow to the end of a single line.

x = -pi:.1:pi;
y = sin(x);
h = plot(x,y);
line2arrow(h);

The arrow will automatically sync if you change line properties, like line width or color.

set(h, 'color', 'red', 'linewidth', 2);

Changes to the axis aspect ratios require a manual resync, either by clicking on the line object or recalling line2arrow.

set(gca, 'dataaspectratio', [2 1 1]);

line2arrow(h);

If you manually change things so the arrowhead and line are out of sync (color-wise), the clash will remain until another sync takes place. So if you want this in your final image, make sure you don't alter the line after setting it as such.

line2arrow(h, 'color', 'b', 'headwidth', 20);