{"id":1925,"date":"2015-01-28T17:58:58","date_gmt":"2015-01-28T17:58:58","guid":{"rendered":"http:\/\/healthmedicinet.com\/news\/parameter-advising-for-multiple-sequence-alignment\/"},"modified":"2015-01-28T17:58:58","modified_gmt":"2015-01-28T17:58:58","slug":"parameter-advising-for-multiple-sequence-alignment","status":"publish","type":"post","link":"http:\/\/healthmedicinet.com\/news\/parameter-advising-for-multiple-sequence-alignment\/","title":{"rendered":"Parameter advising for multiple sequence alignment"},"content":{"rendered":"<h4>Parameter advising<\/h4>\n<p>We apply parameter advising to boost the true accuracy of the Opal aligner 4,5], where the advisor is using parameter sets found by the <span class=\"inlinenumber\"><\/span>-approximation algorithm. Figure 1 shows the accuracy of the advisor for a parameter set of size <em>k = <\/em>10, where the benchmarks are assigned to bins based on their accuracy using a default<br \/>\n         parameter choice; the figure also shows the accuracies when using a single default<br \/>\n         parameter choice, and an oracle. The number of benchmarks per bin is indicated above<br \/>\n         the columns. An <em>oracle <\/em>is an advisor that knows the true accuracy of an alignment; its accuracy is shown<br \/>\n         by the dotted line, which gives the performance of a perfect advisor. Notice that<br \/>\n         in many cases the performance of the estimator is close to the oracle. This is most<br \/>\n         clear on the bin which has lowest average accuracy, where advising increases the average<br \/>\n         accuracy by almost 20% compared to using a single default parameter.\n      <\/p>\n<p><strong>Figure 1.<\/strong> <strong>Advising accuracy of Facet within benchmark bins<\/strong>.\n      <\/p>\n<p>Figure 2 shows the average advising accuracy for parameter sets of various cardinalities using<br \/>\n         as the estimator Facet 3], TCS 6], MOS 7], and PredSP 8], where in the average, benchmark bins contribute equally. The vertical axis is advising<br \/>\n         accuracy on the testing data, averaged over all benchmarks and all folds using 12-fold<br \/>\n         cross-validation. The horizontal axis is the cardinality <em>k <\/em>of the greedy advisor set. Greedy advisor set found by the approximation algorithm<br \/>\n         are augmented from the exact set of cardinality ? = 1 (namely, the best single parameter<br \/>\n         choice). Notice that Facet (the topmost curve in the plot) continues to increase in<br \/>\n         advising accuracy up to cardinality <em>k <\/em>= 6. Notice also that while all of the advisors reach a plateau, for Facet this occurs<br \/>\n         at a greater cardinality and accuracy than for other estimators.\n      <\/p>\n<p><strong>Figure 2.<\/strong> <strong>Average advising accuracy of estimators on sets of varying cardinality<\/strong>.\n      <\/p>\n<h4>Accuracy estimation<\/h4>\n<p>Our tool Facet (<strong>F<\/strong>eature-based <strong>Ac<\/strong>curacy <strong>E<\/strong>s<strong>t<\/strong>imator) 9] is an easy-to-use, open-source utility for estimating the accuracy of a protein multiple<br \/>\n         sequence alignment. Facet evaluates the estimated accuracy of a computed alignment<br \/>\n         as a linear combination of real-valued feature functions. We considered 12 features<br \/>\n         of which we found an optimal subset of 5 that provide the best performance for alignment<br \/>\n         advising. Many of the most useful features utilize information about protein secondary<br \/>\n         structure. We find coefficients by fitting the difference in estimator values to the<br \/>\n         difference in true accuracy for pairs of examples where the correct alignment is known.<br \/>\n         This \u00e2\u20ac\u0153difference fitting\u00e2\u20ac\u009d approach is computationally efficient and yields an estimator<br \/>\n         that works well for advising.\n      <\/p>\n<p>Facet is open-source software that allows users to estimate accuracy as either (1)<br \/>\n         a stand alone tool, or (2) a software library that can be integrated into a pre-existing<br \/>\n         Java application. The implementation provides optimized default coefficients and features.<br \/>\n         These coefficients may also be specified manually and new features can also be added.<br \/>\n         Figure 3 shows a simple example of using Facet within a Java application to choose between<br \/>\n         two alignments of the same set of sequences. The secondary structure predictions are<br \/>\n         computed on the unaligned sequences and can be reused between the two alignments.\n      <\/p>\n<p><strong>Figure 3.<\/strong> <strong>Example of invoking Facet in Java<\/strong>.\n      <\/p>\n<p>The Facet website provides parameter sets that can be used with the Opal aligner (namely<br \/>\n         substitution matrices and affine gap penalties), as well as scripts for structure<br \/>\n         prediction.\n      <\/p>\n","protected":false},"excerpt":{"rendered":"<p>Parameter advising We apply parameter advising to boost the true accuracy of the Opal aligner 4,5], where the advisor is using parameter sets found by the -approximation algorithm. Figure 1 shows the accuracy of the advisor for a parameter set of size k = 10, where the benchmarks are assigned to bins based on their [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1925","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts\/1925","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/comments?post=1925"}],"version-history":[{"count":0,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts\/1925\/revisions"}],"wp:attachment":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/media?parent=1925"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/categories?post=1925"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/tags?post=1925"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}