Use this widget by saying::

<field name="my_field" widget="x2many_2d_matrix" />

This assumes that my_field refers to a model with the fields `x`, `y` and
`value`. If your fields are named differently, pass the correct names as
attributes:

.. code-block:: xml

    <field name="my_field" widget="x2many_2d_matrix" field_x_axis="my_field1" field_y_axis="my_field2" field_value="my_field3">
        <tree>
            <field name="my_field"/>
            <field name="my_field1"/>
            <field name="my_field2"/>
            <field name="my_field3"/>
        </tree>
    </field>

You can pass the following parameters:

field_x_axis
    The field that indicates the x value of a point
field_y_axis
    The field that indicates the y value of a point
field_label_x_axis
    Use another field to display in the table header
field_label_y_axis
    Use another field to display in the table header
field_value
    Show this field as value
show_row_totals
    If field_value is a numeric field, it indicates if you want to calculate
    row totals. True by default
show_column_totals
    If field_value is a numeric field, it indicates if you want to calculate
    column totals. True by default
field_att_<name>
    Declare `disabled` or `hidden` options prefixed with this string as you need for binding a field value with an HTML node attribute called as the <name> passed in the option.

Example
~~~~~~~

You need a data structure already filled with values. Let's assume we want to
use this widget in a wizard that lets the user fill in planned hours for one
task per project per user. In this case, we can use ``project.task`` as our
data model and point to it from our wizard. The crucial part is that we fill
the field in the default function:

.. code-block:: python

    from odoo import fields, models

    class MyWizard(models.TransientModel):
        _name = 'my.wizard'

        def _default_task_ids(self):
            # your list of project should come from the context, some selection
            # in a previous wizard or wherever else
            projects = self.env['project.project'].browse([1, 2, 3])
            # same with users
            users = self.env['res.users'].browse([1, 2, 3])
            return [
                (0, 0, {
                    'name': 'Sample task name',
                    'project_id': p.id,
                    'user_id': u.id,
                    'planned_hours': 0,
                    'message_needaction': False,
                    'date_deadline': fields.Date.today(),
                })
                # if the project doesn't have a task for the user,
                # create a new one
                if not p.task_ids.filtered(lambda x: x.user_id == u) else
                # otherwise, return the task
                (4, p.task_ids.filtered(lambda x: x.user_id == u)[0].id)
                for p in projects
                for u in users
            ]

        task_ids = fields.Many2many('project.task', default=_default_task_ids)

Now in our wizard, we can use:

.. code-block:: xml

    <field name="task_ids" widget="x2many_2d_matrix" field_x_axis="project_id" field_y_axis="user_id" field_value="planned_hours">
        <tree>
            <field name="task_ids"/>
            <field name="project_id"/>
            <field name="user_id"/>
            <field name="planned_hours"/>
        </tree>
    </field>

Note that all values in the matrix must exist, so you need to create them previously if not present, but you can control visually the editability of the fields in the matrix through field_att_disabled option with a control field.