Why in spectral clustering number of eigen vectors is same as number of clusters that we want?












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In spectral clustering we take eigenvector corresponding to K smallest eigenvalues. Then we do K means clustering on these eigenvector to get final clusters. What will happen if we take different number of eigenvectors than number of clusters we want ?










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    -1












    $begingroup$


    In spectral clustering we take eigenvector corresponding to K smallest eigenvalues. Then we do K means clustering on these eigenvector to get final clusters. What will happen if we take different number of eigenvectors than number of clusters we want ?










    share|improve this question







    New contributor




    sneh gupta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      -1












      -1








      -1





      $begingroup$


      In spectral clustering we take eigenvector corresponding to K smallest eigenvalues. Then we do K means clustering on these eigenvector to get final clusters. What will happen if we take different number of eigenvectors than number of clusters we want ?










      share|improve this question







      New contributor




      sneh gupta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      In spectral clustering we take eigenvector corresponding to K smallest eigenvalues. Then we do K means clustering on these eigenvector to get final clusters. What will happen if we take different number of eigenvectors than number of clusters we want ?







      clustering






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      asked 2 days ago









      sneh guptasneh gupta

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          $begingroup$

          Theoretically, log2(k) components could be enough.



          But usually clusters are not that well balanced, that you could get all 2^l combinations of eigenvectors stable, usually one will mask the other.



          If you go back to the theory of spectral clustering, you'd have one eigenvector for each connected component. Now the clusters are unfortunately connected, so we don't completely get this ideal situation, but you'd expect one eigenvector for each "almost component", too.






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          • $begingroup$
            Can you please share the related resource or give intuition behind sqrt(k) components?
            $endgroup$
            – sneh gupta
            yesterday










          • $begingroup$
            Sorry. Log2(k) of course. Enough to separate k components.
            $endgroup$
            – Anony-Mousse
            yesterday











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          $begingroup$

          Theoretically, log2(k) components could be enough.



          But usually clusters are not that well balanced, that you could get all 2^l combinations of eigenvectors stable, usually one will mask the other.



          If you go back to the theory of spectral clustering, you'd have one eigenvector for each connected component. Now the clusters are unfortunately connected, so we don't completely get this ideal situation, but you'd expect one eigenvector for each "almost component", too.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Can you please share the related resource or give intuition behind sqrt(k) components?
            $endgroup$
            – sneh gupta
            yesterday










          • $begingroup$
            Sorry. Log2(k) of course. Enough to separate k components.
            $endgroup$
            – Anony-Mousse
            yesterday
















          1












          $begingroup$

          Theoretically, log2(k) components could be enough.



          But usually clusters are not that well balanced, that you could get all 2^l combinations of eigenvectors stable, usually one will mask the other.



          If you go back to the theory of spectral clustering, you'd have one eigenvector for each connected component. Now the clusters are unfortunately connected, so we don't completely get this ideal situation, but you'd expect one eigenvector for each "almost component", too.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Can you please share the related resource or give intuition behind sqrt(k) components?
            $endgroup$
            – sneh gupta
            yesterday










          • $begingroup$
            Sorry. Log2(k) of course. Enough to separate k components.
            $endgroup$
            – Anony-Mousse
            yesterday














          1












          1








          1





          $begingroup$

          Theoretically, log2(k) components could be enough.



          But usually clusters are not that well balanced, that you could get all 2^l combinations of eigenvectors stable, usually one will mask the other.



          If you go back to the theory of spectral clustering, you'd have one eigenvector for each connected component. Now the clusters are unfortunately connected, so we don't completely get this ideal situation, but you'd expect one eigenvector for each "almost component", too.






          share|improve this answer











          $endgroup$



          Theoretically, log2(k) components could be enough.



          But usually clusters are not that well balanced, that you could get all 2^l combinations of eigenvectors stable, usually one will mask the other.



          If you go back to the theory of spectral clustering, you'd have one eigenvector for each connected component. Now the clusters are unfortunately connected, so we don't completely get this ideal situation, but you'd expect one eigenvector for each "almost component", too.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 23 hours ago

























          answered 2 days ago









          Anony-MousseAnony-Mousse

          4,856624




          4,856624












          • $begingroup$
            Can you please share the related resource or give intuition behind sqrt(k) components?
            $endgroup$
            – sneh gupta
            yesterday










          • $begingroup$
            Sorry. Log2(k) of course. Enough to separate k components.
            $endgroup$
            – Anony-Mousse
            yesterday


















          • $begingroup$
            Can you please share the related resource or give intuition behind sqrt(k) components?
            $endgroup$
            – sneh gupta
            yesterday










          • $begingroup$
            Sorry. Log2(k) of course. Enough to separate k components.
            $endgroup$
            – Anony-Mousse
            yesterday
















          $begingroup$
          Can you please share the related resource or give intuition behind sqrt(k) components?
          $endgroup$
          – sneh gupta
          yesterday




          $begingroup$
          Can you please share the related resource or give intuition behind sqrt(k) components?
          $endgroup$
          – sneh gupta
          yesterday












          $begingroup$
          Sorry. Log2(k) of course. Enough to separate k components.
          $endgroup$
          – Anony-Mousse
          yesterday




          $begingroup$
          Sorry. Log2(k) of course. Enough to separate k components.
          $endgroup$
          – Anony-Mousse
          yesterday










          sneh gupta is a new contributor. Be nice, and check out our Code of Conduct.










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