Defining options

In PGFPlots, options are given as a list of keys that might have corresponding values inside of two square brackets e.g.

\begin{axis}[ybar, width = 4.5cm]
...
\end{axis}

This section shows the method for which to set and retrieve such options.

Setting options when constructing an object

As arguments to the constructor

When constructing an object (like a Plot), options to that object can be entered in the argument list where a string represents a key without a value (e.g. "very thick") and a pair represents a key/value option, (e.g. "samples" => 50). This works well when the options are few and there is only one level of options in the object.

julia> c = pgf.Coordinates([1,2,3], [2, 4, 8]);

julia> p = pgf.Plot(c, "very thick", "mark" => "halfcircle")

julia> pgf.print_tex(p); # print_tex is typically not called from user code
\addplot+[very thick, mark={halfcircle}]
        coordinates {
        (1, 2)
        (2, 4)
        (3, 8)
        }
    ;

The @pgf macro

When there are nested options the previous method does not work so well. Instead, we provide a macro @pgf so that options can be entered similarly to how they are in tex.

The previous example is then written as

pgf.@pgf pgf.Plot(c,
    {
        very_thick,
        mark = "halfcircle"
    })

A more complicated example is:

pgf.@pgf a = pgf.Axis(pgf.Plot(c),
    {
        "axis background/.style" =
        {
            shade,
            top_color = "gray",
            bottom_color = "white",
        },
        ymode = "log"
    }
)

which is printed as

julia> pgf.print_tex(a)
    \begin{axis}[axis background/.style={shade, top color={gray}, bottom color={white}}, ymode={log}]
        \addplot+[]
            coordinates {
            (1, 2)
            (2, 4)
            (3, 8)
            }
        ;
    \end{axis}

The macro can be applied to any type of expression and will be applied to everything inside that expression that is of the form { expr }.

!!!note * Keys that contain symbols that in Julia are operators (e.g the key "axis background/.style") has to be entered as strings, as in the example above.

Transformations

The following transformations of keys/values are done when the options are written in .tex style:

• Underlines in keys are replaced with spaces e.g. very_thick -> "very thick".

• A list as a value is written as "comma joined" e.g. [1, 2, 3] -> "1, 2, 3".

• A tuple as a value is written with braces delimiting the elements e.g. (60, 30) -> {60}{30}

Modifying options after an object is created

It is sometimes convenient to set and get options after an object has been created.

julia> c = pgf.Coordinates([1,2,3], [2, 4, 8]);

julia> p = pgf.Plot(c)

julia> p["fill"] = "blue";

julia> p["fill"];
"blue"

julia> pgf.@pgf p["axis background/.style"] = { shade, top_color = "gray", bottom_color = "white" };

julia> p["axis background/.style"]["top_color"];
"gray"

julia> p["very thick"] = nothing # Set a value less options;

julia> delete!(p, "fill");

julia> p

julia> pgf.print_tex(p)
    \addplot+[axis background/.style={shade, top color={gray}, bottom color={white}}, very tick]
        coordinates {
        (1, 2)
        (2, 4)
        (3, 8)
        }
    ;

You can also merge in options that have been separately created using merge!

julia> a = pgf.Axis();

julia> pgf.@pgf opts =  {xmin = 0, ymax = 1, ybar};

julia> merge!(a, opts)

julia> pgf.print_tex(a)
    \begin{axis}[xmin={0}, ymax={1}, ybar]
    \end{axis}

It is then easy to apply for example a "theme" to an axis where the themed is a set of options already saved.