.. _book_fig_chapter7_fig_PCA_LLE:


PCA Projection of SDSS Spectra
------------------------------
Figure 7.9

A comparison of the classification of quiescent galaxies and sources with
strong line emission using LLE and PCA. The top panel shows the segregation of
galaxy types as a function of the first three PCA components. The lower panel
shows the segregation using the first three LLE dimensions. The preservation of
locality in LLE enables nonlinear features within a spectrum (e.g., variation
in the width of an emission line) to be captured with fewer components. This
results in better segregation of spectral types with fewer dimensions.



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.. image:: ../images/chapter7/fig_PCA_LLE_1.png
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.. image:: ../images/chapter7/fig_PCA_LLE_2.png
    :align: center
    :scale: 100



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**Python source code:**

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