LineSpec to quickly customize the lines appearance in a plot

## Description

The `LineSpec` is an optional argument that can be used inside a `plot` command to customize each new line aspect. It has to be given as a concatenated string containing information about color, line style or markers. It is very useful to quickly specify such basic line properties.

To specify a red longdash-dot with diamond marker, the string can be `'r-.diam'`. As you can see, a full complete spelling of each property value is not required but the string, which is a concatenation (in any order) of these three types of properties, must remain unambiguous. Furthermore, the string specification is not case sensitive.

Here is a complete list of the `LineSpec` types you can specify (using plot).

LineStyle:

  a string defining the line style. This property is linked to the object's `line_style` property (see polyline properties).

  `Specifier` | `Line Style`
  `-` | Solid line (default)
  `--` | Dashed line
  `:` | Dotted line
  `-.` | Dash-dotted line

Color:

  a string defining the line color. This property is linked to the object's `foreground` property (see polyline properties).

  `Specifier` | `Color`
  `r` | Red
  `g` | Green
  `b` | Blue
  `c` | Cyan
  `m` | Magenta
  `y` | Yellow
  `k` | Black
  `w` | White

  A default color table is used to color plotted curves if you do not specify a color (neither with `LineSpec` nor with GlobalProperty). When drawing multiple lines, the plot command automatically cycles through this table. Here are the used colors:

  `R` | `G` | `B`
  0. | 0. | 1.
  0. | 0.5 | 0.
  1. | 0. | 0.
  0. | 0.75 | 0.75
  0.75 | 0. | 0.75
  0.75 | 0.75 | 0.
  0.25 | 0.25 | 0.25

Marker type:

  A string defining the marker type. Note that if you specify a marker without a line style, only the marker is drawn. This property is linked to the object's `mark_style` and `mark_mode` properties (see polyline properties).

  `Specifier` | `Marker Type`
  `+` | Plus sign
  `o` | Circle
  `*` | Asterisk
  `.` | Point
  `x` | Cross
  `'square'` or `'s'` | Square
  `'diamond'` or `'d'` | Diamond
  `^` | Upward-pointing centered triangle
  `v` | Downward-pointing centered triangle
  `>` | Right-pointing centered triangle
  `<` | Left-pointing centered triangle
  `'pentagram' or 'p'` | Five-pointed star (pentagram)
  `^.` | Upward-pointing triangle
  `v.` | Downward-pointing triangle
  `>.` | Right-pointing triangle
  `<.` | Left-pointing triangle
  `'minus' or 'm'` | Horizontal line (Minus sign)
  `|` | Vertical line
  | No marker (default)

## Examples

    clf();
    x=1:0.1:10; // Init.
    plot(x,sin(x),'r-.>') // plots a dash-dotted line with a right-pointing triangle centered on each points.

x=1:0.1:10; // Init. plot(x,sin(x),'r.->') t=0:%pi/20:2*%pi; plot(t,sin(t),'ro-.',t,cos(t),'cya+',t,abs(sin(t)),'--mo')

    clf();
    x=1:0.1:10;
    // If you specify a marker without a line style, only the marker is drawn
    plot(x,sin(x),'d')

x=1:0.1:10; plot(x,sin(x),'d')

    clf();
    x = 1:0.5:10; // Init.
    // The order of information about color, line style or markers does not matter
    // BUT the information must be unambiguous
    subplot(311);plot(x,sin(x),'.b-');
    subplot(312);plot(x,sin(x),'b.-');
    subplot(313);plot(x,sin(x),'b-.');// The point belongs to information about line style (not marker!)

x = 1:0.5:10; subplot(311);plot(x,sin(x),'.b-'); subplot(312);plot(x,sin(x),'b.-'); subplot(313);plot(x,sin(x),'b-.');

    //multiple plots with different LineSpecs
    clf();
    t=0:%pi/20:2*%pi;
    plot(t,sin(t),'ro-.',t,cos(t),'cya+',t,abs(sin(t)),'--mo')

t=0:%pi/20:2*%pi; plot(t,sin(t),'ro-.',t,cos(t),'cya+',t,abs(sin(t)),'--mo')

## See also

- color
- GlobalProperty
- plot
- clf