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:
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from pipe_control.plotting import write_xy
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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().