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-====== Diversity selection ======
-This filter selects the most diverse compounds from large compound collections by eliminating of the most similar structures. The size of the input collection is decreased, while the maximum possible coverage of its represented chemical space is retained.
-===== When to use =====
-If you have limited experimental or computational resources, diversity selection is an unbiased way to limit the number of compounds to handle. Collecting compounds from different regions of the chemical space is an efficient strategy to maximize the diversity of the identified active scaffolds.
-Using this filter you can either reduce the size of large (virtual) screening libraries, or select a diverse, representative set of your virtual hits.
-===== How to use =====
-It is recommended to apply structural or phys-chem property filters prior to diversity selection to eliminate unwanted structures. This is important to avoid exotic structures that are typically identified as very diverse by the algorithm.
-==== Basic options ====
-The following options can be used to control the diversity of the resulting collection.
-  * **Similarity threshold**: the maximum S similarity allowed in the diverse set. It is guaranteed that none of the resulting molecules are more similar than S.
-  * **Number of most diverse molecules**: the maximum N number of diverse molecules to be selected. The diversity selection algorithm will select the most diverse N molecules, unless the maximum allowed similarity is reached first.
-If you do not limit the selection, the full collection will be returned ordered by diversity. This means that the top N molecules in the resulting collection will be the most diverse N molecules. The //maximum similarity// found at the Nth molecule in the results will refer to the minimum diversity of the first N molecules (none of them are more similar than that value).
-==== Advanced options ====
-Under Advanced options, you can adjust the definition of similarity/dissimilarity of molecules. You can select the descriptor used for calculating the similarity scores. Currently two fingerprints (OpenBabel Linear Fingerprint and Indigo Similarity Fingerprint) are available.
-You will be able to set different similarity metrics as the measure of similarity. Currently, only the Tanimoto coefficient (Jaccard index)((http://en.wikipedia.org/wiki/Jaccard_index)) is implemented as the measure of similarity.
-We plan to introduce more descriptors and more similarity measure types in the future.
-  * **Molecular descriptor**: the molecular descriptor applied for representing chemical structures during the calculation
-==== Default options ====
-The default descriptor used is the linear fingerprint implemented in Open Babel ((Open Babel v2.3.90 http://openbabel.sourceforge.net/)), which is similar to Daylight’s fingerprint and Chemaxon’s linear fingerprint, and the Tanimoto coefficient is calculated as the similarity of fingerprints.
-If you have no suggestions to use another setup, you can rely on our choices. After implementation and evaluation of new fingerprints and metrics, the default setup can be changed. This can be tracked at the end of this document, in the Changelog section.
-==== Algorithm ====
-We use an optimized implementation of the stepwise elimination algorithm((R. J. Taylor, J. Chem. Inf. Comput. Sci., 1995, 35, 59 67.)), which can be described as follows:
-  - calculate the similarity matrix of the molecules in the input collection
-  - process the matrix elements as follows:
-    - select the largest off-diagonal element in the similarity matrix
-    - eliminate one molecule of the most similar molecule pair randomly
-    - go to step I. if off-diagonal elements remained
-  - sort the list of eliminated molecules by similarity values associated to the elimination steps in increasing order
-During this process, the size of the collection is reduced and diversity increases. Each elimination step throws out a compound that has close analogues in the remaining set. In result, we get a single compound, and a list of compounds with decreasing similarity values, which can be interpreted as the increasing diversity of the remaining set.
-After the algorithm finishes, structures are sorted by similarity values and are placed in the result collection. The first molecules in the resulted collection are the most dissimilar (most diverse) ones, and the length of the result list is determined using the diversity options: the maximum number of compounds to be selected and the maximum similarity values allowed between diverse compounds.
-===== Limitations =====
-The diversity selection is freely accessible for every mcule user with a monthly limit of 10000 input compounds. The average run time for 10000 compouds is about 5 minutes. The usage of your diversity filter can be tracked on the user profile / limits. Our technologies allow effective processing of very large collections (~10M). If you want to exceed your limits, please contact us.
-===== Changelog =====
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