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<!--
- * Jalview - A Sequence Alignment Editor and Viewer (Version 2.9.0b1)
- * Copyright (C) 2015 The Jalview Authors
+ * Jalview - A Sequence Alignment Editor and Viewer ($$Version-Rel$$)
+ * Copyright (C) $$Year-Rel$$ The Jalview Authors
*
* This file is part of Jalview.
*
<p>
<strong>Principal Component Analysis</strong>
</p>
+ <p>A principal component analysis can be performed via the
+ <a href="calculations.html">calculations dialog</a> which is accessed by selecting <strong>Calculate→Calculate
+ Tree or PCA...</strong>.</p>
<p>This calculation creates a spatial representation of the
similarities within a selected group, or all of the sequences in an
alignment. After the calculation finishes, a 3D viewer displays the
set of sequences as points in 'similarity space', and similar
sequences tend to lie near each other in the space.</p>
<p>
- <em>Caveats</em><br />The calculation is computationally expensive,
- and may fail for very large sets of sequences - usually because the
- JVM has run out of memory. A future release of Jalview will be able
- to avoid this by executing the calculation via a web service.
+ <em>Caveats</em><br />The calculation can be computationally
+ expensive, and may fail for very large sets of sequences - usually
+ because the JVM has run out of memory. However, the PCA
+ implementation in Jalview 2.10.2 employs more memory efficient
+ matrix storage structures, allowing larger PCAs to be performed.
</p>
<p>
pair of sequences - computed with one of the available score
matrices, such as <a href="scorematrices.html#blosum62">BLOSUM62</a>,
<a href="scorematrices.html#pam250">PAM250</a>, or the <a
- href="scorematrices.html#simplenucleotide"
- >simple single nucleotide substitution matrix</a>. The options
- available for calculation are given in the <strong><em>Change
+ href="scorematrices.html#simplenucleotide">simple single
+ nucleotide substitution matrix</a>. The options available for
+ calculation are given in the <strong><em>Change
Parameters</em></strong> menu.
</p>
<p>
- <em>PCA Calculation modes</em><br /> The default Jalview calculation
- mode (indicated when <em><strong>Jalview PCA
- Calculation</strong></em> is ticked in the <strong><em>Change
+ <em>PCA Calculation modes</em><br /> The default Jalview
+ calculation mode (indicated when <em><strong>Jalview
+ PCA Calculation</strong></em> is ticked in the <strong><em>Change
Parameters</em></strong> menu) is to perform a PCA on a matrix where elements
in the upper diagonal give the sum of scores for mutating in one
direction, and the lower diagonal is the sum of scores for mutating
gives an asymmetric matrix, and a different PCA to a matrix produced
with the method described in the paper by G. Casari, C. Sander and
A. Valencia. Structural Biology volume 2, no. 2, February 1995 (<a
- href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7749921"
- >pubmed</a>) and implemented at the SeqSpace server at the EBI. This
- method preconditions the matrix by multiplying it with its
- transpose, and can be employed in the PCA viewer by unchecking the <strong><em>Jalview
+ href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=7749921">pubmed</a>)
+ and implemented at the SeqSpace server at the EBI. This method
+ preconditions the matrix by multiplying it with its transpose, and
+ can be employed in the PCA viewer by unchecking the <strong><em>Jalview
PCA Calculation</em></strong> option in the <strong><em>Change
Parameters</em></strong> menu.
</p>
git://source.jalview.org / jalview.git / blobdiff