tools/pca.py

from sklearn.decomposition import PCA
import numpy as np
import plotly.express as px


def pca(matches, identities, gallery, dim=3):
    """
    Perform PCA on embeddings.
    Args:
        embeddings: np.array of shape (n_embeddings, 512)
    Returns:
        embeddings_pca: np.array of shape (n_embeddings, 3)
    """

    # Get Gallery and Detection Embeddings and stich them together in groups
    embeddings = np.concatenate(
        [[gallery[match.gallery_idx].embedding, identities[match.identity_idx].embedding] for match in matches],
        axis=0,
    )

    # Get Identity Names and stich them together in groups
    identity_names = np.concatenate(
        [[gallery[match.gallery_idx].name, gallery[match.gallery_idx].name] for match in matches],
        axis=0,
    )

    # Do 3D PCA
    pca = PCA(n_components=dim)
    pca.fit(embeddings)
    embeddings_pca = pca.transform(embeddings)

    if dim == 3:
        fig = px.scatter_3d(
            embeddings_pca,
            x=0,
            y=1,
            z=2,
            opacity=0.7,
            color=identity_names,
            color_discrete_sequence=px.colors.qualitative.Vivid,
        )
        fig.update_traces(marker=dict(size=4))
    elif dim == 2:
        fig = px.scatter(
            embeddings_pca,
            x=0,
            y=1,
            opacity=0.7,
            color=identity_names,
            color_discrete_sequence=px.colors.qualitative.Vivid,
        )
        fig.update_traces(marker=dict(size=4))
        fig.update_xaxes(showgrid=True)
        fig.update_yaxes(showgrid=True)
    else:
        raise ValueError("dim must be either 2 or 3")
    fig.update_layout(margin=dict(l=0, r=0, b=0, t=0))

    return fig