Label Points

Use string arrays in a point set to label points

import numpy as np
import pyvista as pv
from pyvista import examples

The pyvista.Plotter.add_point_labels() method makes it easy to add point labels to a scene.

help(pv.Plotter.add_point_labels)

Help on function add_point_labels in module pyvista.plotting.plotting:

add_point_labels(self, points, labels, italic=False, bold=True, font_size=None, text_color=None, font_family=None, shadow=False, show_points=True, point_color=None, point_size=None, name=None, shape_color='grey', shape='rounded_rect', fill_shape=True, margin=3, shape_opacity=1.0, pickable=False, render_points_as_spheres=False, tolerance=0.001, reset_camera=None, always_visible=False, render=True)
    Create a point actor with one label from list labels assigned to each point.

    Parameters
    ----------
    points : sequence or pyvista.DataSet or vtk.vtkAlgorithm
        An ``n x 3`` sequence points or pyvista dataset with points or
        mesh-producing algorithm.

    labels : list or str
        List of labels.  Must be the same length as points. If a
        string name is given with a :class:`pyvista.DataSet` input for
        points, then these are fetched.

    italic : bool, optional
        Italicises title and bar labels.  Default ``False``.

    bold : bool, optional
        Bolds title and bar labels.  Default ``True``.

    font_size : float, optional
        Sets the size of the title font.  Defaults to 16.

    text_color : ColorLike, optional
        Color of text. Either a string, RGB sequence, or hex color string.

        * ``text_color='white'``
        * ``text_color='w'``
        * ``text_color=[1.0, 1.0, 1.0]``
        * ``text_color='#FFFFFF'``

    font_family : str, optional
        Font family.  Must be either ``'courier'``, ``'times'``,
        or ``'arial``.

    shadow : bool, optional
        Adds a black shadow to the text.  Defaults to ``False``.

    show_points : bool, optional
        Controls if points are visible.  Default ``True``.

    point_color : ColorLike, optional
        Either a string, rgb list, or hex color string.  One of
        the following.

        * ``point_color='white'``
        * ``point_color='w'``
        * ``point_color=[1.0, 1.0, 1.0]``
        * ``point_color='#FFFFFF'``

    point_size : float, optional
        Size of points if visible.

    name : str, optional
        The name for the added actor so that it can be easily
        updated.  If an actor of this name already exists in the
        rendering window, it will be replaced by the new actor.

    shape_color : ColorLike, optional
        Color of shape (if visible).  Either a string, rgb
        sequence, or hex color string.

    shape : str, optional
        The string name of the shape to use. Options are ``'rect'`` or
        ``'rounded_rect'``. If you want no shape, pass ``None``.

    fill_shape : bool, optional
        Fill the shape with the ``shape_color``. Outlines if ``False``.

    margin : int, optional
        The size of the margin on the label background shape. Default is 3.

    shape_opacity : float, optional
        The opacity of the shape in the range of ``[0, 1]``.

    pickable : bool, optional
        Set whether this actor is pickable.

    render_points_as_spheres : bool, optional
        Render points as spheres rather than dots.

    tolerance : float, optional
        A tolerance to use to determine whether a point label is
        visible.  A tolerance is usually required because the
        conversion from world space to display space during
        rendering introduces numerical round-off.

    reset_camera : bool, optional
        Reset the camera after adding the points to the scene.

    always_visible : bool, optional
        Skip adding the visibility filter. Default False.

    render : bool, optional
        Force a render when ``True`` (default).

    Returns
    -------
    vtk.vtkActor2D
        VTK label actor.  Can be used to change properties of the labels.

    Examples
    --------
    >>> import numpy as np
    >>> import pyvista
    >>> pl = pyvista.Plotter()
    >>> points = np.array([[0.0, 0.0, 0.0],
    ...                    [1.0, 1.0, 0.0],
    ...                    [2.0, 0.0, 0.0]])
    >>> labels = ['Point A', 'Point B', 'Point C']
    >>> actor = pl.add_point_labels(points, labels, italic=True, font_size=20,
    ...                             point_color='red', point_size=20,
    ...                             render_points_as_spheres=True,
    ...                             always_visible=True, shadow=True)
    >>> pl.camera_position = 'xy'
    >>> pl.show()

Label Point Cloud

Let’s make a random point cloud and label each point in 3D space

# Make some random points
poly = pv.PolyData(np.random.rand(10, 3))

Add string labels to the point data - this associates a label with every node:

poly["My Labels"] = [f"Label {i}" for i in range(poly.n_points)]
poly

Header	Data Arrays
PolyData Information N Cells 10 N Points 10 N Strips 0 X Bounds 4.404e-03, 6.464e-01 Y Bounds 6.402e-02, 9.706e-01 Z Bounds 9.953e-02, 9.460e-01 N Arrays 1	Name Field Type N Comp Min Max My Labels Points 1 nan nan

Now plot the points with labels using pyvista.Plotter.add_point_labels()

# (your code here, answer below)

plotter = pv.Plotter()
plotter.add_point_labels(poly, "My Labels", point_size=20, font_size=36)
plotter.show()

Label Node Locations

This example will label the nodes of a mesh with their coordinate locations

# Load example beam file
grid = pv.UnstructuredGrid(examples.hexbeamfile)

Create plotting class and add the unstructured grid

plotter = pv.Plotter()
plotter.add_mesh(grid, show_edges=True, color="tan")

# Add labels to points on the yz plane (where x == 0)
points = grid.points
mask = points[:, 0] == 0
plotter.add_point_labels(points[mask], points[mask].tolist(), point_size=20, font_size=36)

plotter.camera_position = [(-1.5, 1.5, 3.0), (0.05, 0.6, 1.2), (0.2, 0.9, -0.25)]

plotter.show()

Label Scalar Values

This example will label each point with their scalar values

mesh = examples.load_uniform().slice()

p = pv.Plotter()

# Add the mesh:
p.add_mesh(mesh, scalars="Spatial Point Data", show_edges=True)
# Add the points with scalar labels:
p.add_point_scalar_labels(mesh, "Spatial Point Data", point_size=20, font_size=36)

# Use a nice camera position:
p.camera_position = [(7, 4, 5), (4.4, 7.0, 7.2), (0.8, 0.5, 0.25)]

p.show()