== Packages ==
The flow of execution for plotting XY-type data in relax is:
* The [http://www.nmr-relax.com/api/3.3/lib.plotting-module.html lib.plotting] functions write_xy_header() and write_xy_data().
=== Package: user_functions ===
The user interface for plotting are generally the user functions. Currently this consists of the [http://www.nmr-relax.com/manual/grace_write.html grace.write] and [http://www.nmr-relax.com/manual/dx_map.html dx.map] user functions. However in the future a software independent interface will be gradually implemented via a new plotting user function class. An idea would be to have one user function per graph type, for example:
The [http://www.nmr-relax.com/api/3.3/user_functions-module.html user_functions package] consists of definitions that are used to construct the prompt or graphical UI and to set up automated argument checking.
=== Package: pipe_control ===
The user functions provide a simple interface to the relax backend. For plotting and most functionality, this is in the [http://www.nmr-relax.com/api/3.3/pipe_control-module.html pipe_control package] which is used primarily to read and write data to the relax data store. However power-users can bypass the user function interface and directly use the backend code for greater functionality. This also allows for the implementation of new features without modifying the user interface. To use the backend code, for example for plotting XY-type data, one needs to import:
The write_xy() function will assemble the data from the relax data store via the [http://www.nmr-relax.com/api/3.3/pipe_control.plotting-module.html#assemble_data assemble_data() function]. It will then call the plotting API functions write_xy_header() and write_xy_data().
=== Package: lib ===
The plotting API is located in the [http://www.nmr-relax.com/api/3.3/lib.plotting-module.html lib.plotting relax library package]. The API is defined within the [http://www.nmr-relax.com/api/3.3/lib.plotting.api-module.html lib.plotting.api module]. This consists of a collection of plotting functions, each of which accepts the 'format' argument. The format argument is then used to determine which function in which module in lib.plotting will be called. For example see the [http://www.nmr-relax.com/api/3.3/lib.plotting.api-pysrc.html#correlation_matrix correlation_matrix() function].
To implement a new plotting feature for a certain software package, for example for Gnuplot, an equivalent function should be provided in the [http://www.nmr-relax.com/api/3.3/lib.plotting.gnuplot-module.html lib.plotting.gnuplot module]. This should have the same name as the API function and accept exactly the same arguments, excluding the format argument.
== Development ==
To add a new plotting feature, the following steps are required: