The normalize() function

Each base section defined using the NOMAD schema has a set of public functions which can be used at any moment when reading and parsing files in NOMAD. The normalize(archive, logger) function is a special case of such functions, which warrants an in-depth description.

This function is run within the NOMAD infrastructure by the MetainfoNormalizer in the following order:

1. A child section's normalize() function is run before their/its parents' normalize() function.
2. For sibling sections, the normalize() function is executed from the smaller to the larger normalizer_level attribute. If normalizer_level is not set or if they are the same for two different sections, the order is established by the attributes definition order in the parent section.
3. Using super().normalize(archive, logger) runs the inherited section normalize function.

Let's see some examples. Imagine having the following Section and SubSection structure:

from nomad.datamodel.data import ArchiveSection


class Section1(ArchiveSection):
    normalizer_level = 1

    def normalize(self, achive, logger):
        # some operations here
        pass


class Section2(ArchiveSection):
    normalizer_level = 0

    def normalize(self, achive, logger):
        super().normalize(archive, logger)
        # Some operations here or before `super().normalize(archive, logger)`


class ParentSection(ArchiveSection):

    sub_section_1 = SubSection(Section1.m_def, repeats=False)

    sub_section_2 = SubSection(Section2.m_def, repeats=True)

    def normalize(self, achive, logger):
        super().normalize(archive, logger)
        # Some operations here or before `super().normalize(archive, logger)`

Now, MetainfoNormalizer will be run on the ParentSection. Applying rule 1, the normalize() functions of the ParentSection's childs are executed first. The order of these functions is established by rule 2 with the normalizer_level atrribute, i.e., all the Section2 (note that sub_section_2 is a list of sections) normalize() functions are run first, then Section1.normalize(). Then, the order of execution will be:

1. Section2.normalize()
2. Section1.normalize()
3. ParentSection.normalize()

In case we do not assign a value to Section1.normalizer_level and Section2.normalizer_level, Section1.normalize() will run first before Section2.normalize(), due to the order of SubSection attributes in ParentSection. Thus the order will be in this case:

1. Section1.normalize()
2. Section2.normalize()
3. ParentSection.normalize()

By checking on the normalize() functions and rule 3, we can establish whether ArchiveSection.normalize() will be run or not. In Section1.normalize(), it will not, while in the other sections, Section2 and ParentSection, it will.