Some screenshots of Facets in the interfaces of different Elsevier products:
Science Direct:
Scopus:
The parameter 'facets' is a list of fields with an optional depth of categories that should be returned:
facets=nav_1 ([count=number,][sort=sortspec,][prefix=filter]);nav_2(...);nav_3(...);...
a) nav_n must be valid facet name sent to the appropriate API cluster (see tables in following sections). Invalid facets will be ignored. Parameter scomode=on is required for this feature.
b) count=number is optional, where number indicates the number of facet entries to be returned. The number will be truncated if it exceeds the maximum allowed based upon entitlement settings.
c) sort=sortspec is optional, where sortspec is one of the codes listed here:
sortspec | Sort by... |
---|---|
na | Modifier name, ascending |
fd | Modifier frequency, descending |
fdna | Modifier frequency descending, secondary sort through unity by name, ascending |
Returned modifiers for nav_n are sorted according to sortspec. If sort parameter is not used, default sortspec is fd for all navigators except the scopubyrnav. The scopubyrnav defaults to sort by name in descending order.
d) prefix=filter is optional, where filter is a sequence of one or more alpha-numeric characters. Returned modifiers for nav_n are limited to those starting with filter. Only prefix filtering is possible, and filtering is case-sensitive and sensitive to the use of accented characters. The prefix will be ignored if filter contains spaces or non-alphanumeric characters.
e) The sort and prefix parameters are applied independently for each facet nav_n specified.
f) If prefix parameter is not used, modifiers are not filtered.
g) If a facet is not listed, it will not be included in the result.
Obviously, this is quite a lot of rules...here is an example that might help clear up some of the above:
The Request:
http://api.elsevier.com/content/search/scopus?query=heart&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&count=1
This request takes each specified facet and limits the search results by the specified count. This is a fairly typical application of facets.
The Response:
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:prism="http://prismstandard.org/namespaces/basic/2.0/"> <title>SCOPUS Search Results: heart</title> <updated>2011-05-23T20:20:06.847Z</updated> <author> <name>Elsevier, Inc.</name> </author> <id>http://api.elsevier.com:80/content/search/scopus?query=heart&count=1&start=0&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&view=STANDARD&field=</id> <opensearch:totalResults>2335755</opensearch:totalResults> <opensearch:startIndex>0</opensearch:startIndex> <opensearch:itemsPerPage>1</opensearch:itemsPerPage> <opensearch:Query role="request" searchTerms="heart" startPage="0"/> <link href="http://api.elsevier.com:80/content/search/scopus?query=heart&start=0&count=1&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&view=STANDARD&field=" ref="self" type="application/atom+xml"/> <link href="http://api.elsevier.com:80/content/search/scopus?query=heart&start=0&count=1&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&view=STANDARD&field=" ref="first" type="application/atom+xml"/> <link href="http://api.elsevier.com:80/content/search/scopus?query=heart&start=1&count=1&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&view=STANDARD&field=" ref="next" type="application/atom+xml"/> <link href="http://api.elsevier.com:80/content/search/scopus?query=heart&start=2335754&count=1&facets=pubyear(count=3);doctype();subjarea(count=5);language(count=4);af_id(count=10);exactkeyword(count=20);srctype()&view=STANDARD&field=" ref="last" type="application/atom+xml"/> <entry> <link href="http://api.elsevier.com/content/abstract/scopus_id/78649662114" ref="self"/> <link href="http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=78649662114" ref="scopus"/> <link href="http://www.scopus.com/inward/citedby.url?partnerID=HzOxMe3b&scp=78649662114" ref="scopus-citedby"/> <prism:url>http://api.elsevier.com/content/abstract/scopus_id/78649662114</prism:url> <dc:identifier>scopus_id/78649662114</dc:identifier> <dc:title>Heart failure severity, as determined by loop diuretic dosages, predicts the risk of developing diabetes after myocardial infarction: A nationwide cohort study</dc:title> <dc:creator>Andersson, C.</dc:creator> <prism:publicationName>European Journal of Heart Failure</prism:publicationName> <prism:issn>13889842 18790844</prism:issn> <prism:volume>12</prism:volume> <prism:issueIdentifier>12</prism:issueIdentifier> <prism:pageRange>1333-1338</prism:pageRange> <prism:coverDate>2010-12-01</prism:coverDate> <prism:doi>10.1093/eurjhf/hfq160</prism:doi> <citedby-count>1</citedby-count> <affiliation/> <affiliation> <affilname>Steno Diabetes Center | Steno Diabetes Center ^</affilname> </affiliation> <affiliation/> <prism:aggregationType>Journal</prism:aggregationType> <subtype>ar</subtype> </entry> <facet> <name>pubyear</name> <attribute>scopubyr</attribute> <category> <name>2843</name> <hitCount>1</hitCount> </category> <category> <name>2826</name> <hitCount>1</hitCount> </category> <category> <name>2823</name> <hitCount>1</hitCount> </category> </facet> <facet> <name>doctype</name> <attribute>scosubtype</attribute> <category> <name>ar</name> <hitCount>1574282</hitCount> </category> <category> <name>re</name> <hitCount>248392</hitCount> </category> <category> <name>cp</name> <hitCount>101272</hitCount> </category> </facet> <facet> <name>subjarea</name> <attribute>scosubjabbr</attribute> <category> <name>MEDI</name> <hitCount>1603190</hitCount> </category> <category> <name>BIOC</name> <hitCount>453693</hitCount> </category> <category> <name>PHAR</name> <hitCount>166349</hitCount> </category> <category> <name>NEUR</name> <hitCount>77340</hitCount> </category> <category> <name>AGRI</name> <hitCount>67425</hitCount> </category> </facet> <facet> <name>language</name> <attribute>scolang</attribute> <category> <name>English</name> <hitCount>1814987</hitCount> </category> <category> <name>German</name> <hitCount>79727</hitCount> </category> <category> <name>French</name> <hitCount>55877</hitCount> </category> <category> <name>Russian</name> <hitCount>47651</hitCount> </category> </facet> <facet> <name>exactkeyword</name> <attribute>scoexactkeywords</attribute> <category> <name>Human</name> <hitCount>1425177</hitCount> </category> <category> <name>Article</name> <hitCount>1302150</hitCount> </category> <category> <name>Male</name> <hitCount>876933</hitCount> </category> <category> <name>Priority journal</name> <hitCount>845313</hitCount> </category> <category> <name>Humans</name> <hitCount>841536</hitCount> </category> <category> <name>Female</name> <hitCount>755270</hitCount> </category> <category> <name>Adult</name> <hitCount>647498</hitCount> </category> <category> <name>Controlled study</name> <hitCount>541073</hitCount> </category> <category> <name>Nonhuman</name> <hitCount>415788</hitCount> </category> <category> <name>Aged</name> <hitCount>391236</hitCount> </category> <category> <name>Animals</name> <hitCount>317486</hitCount> </category> <category> <name>Major clinical study</name> <hitCount>301733</hitCount> </category> <category> <name>Heart</name> <hitCount>290208</hitCount> </category> <category> <name>Middle Aged</name> <hitCount>288122</hitCount> </category> <category> <name>Review</name> <hitCount>250527</hitCount> </category> <category> <name>Animal</name> <hitCount>247381</hitCount> </category> <category> <name>Animal experiment</name> <hitCount>213232</hitCount> </category> <category> <name>Clinical article</name> <hitCount>182021</hitCount> </category> <category> <name>Case report</name> <hitCount>180947</hitCount> </category> <category> <name>Rat</name> <hitCount>178214</hitCount> </category> </facet> <facet> <name>srctype</name> <attribute>scosrctype</attribute> <category> <name>j</name> <hitCount>2151361</hitCount> </category> <category> <name>p</name> <hitCount>25638</hitCount> </category> <category> <name>k</name> <hitCount>14380</hitCount> </category> </facet> </feed>
Different facets are available to the RESTful APIs depending on which cluster is searched.
Field | Facet Name | Default number of values to return counts for | Maximum number of values to return counts for | Sorting |
---|---|---|---|---|
Content type, using label | contenttype | All | All | Journal, Book, Reference Work |
Journal/Book title | srctitle | 5 | 20 | Result count, descending |
Year | pubyr | 5 | 20; if there are more than 20 years, the last result count will be for "Year X and before" (similar to what ScienceDirect does). | Year, descending |
Topics | topics | X | X | X |
Field | Facet Name | Default number of values to return counts for | Maximum number of values to return counts for | Sorting |
---|---|---|---|---|
Source title | exactsrctitle | 3 | 30 | Result count, descending |
Author name, based on author ID, but showing the name | au-id | 3 | 30 | Result count, descending |
Year | pubyear | 3 | 30 | Year, descending |
Document type, using label | doctype | 3 | All | Result count, descending |
Subject area, using label | subjarea | 5 | All | Result count, descending |
Language, using label | language | 3 | All | Result count, descending |
Affiliation, based on affiliation ID, but showing affiliation name | af-id | 3 | 30 | Result count, descending |
Keyword | exactkeyword | 3 | All | Result count, descending |
Source type, using label | srctype | 3 | 30 | Result count, descending |
Field | Facet Name | Default number of values to return counts for | Maximum number of values to return counts for | Sorting |
---|---|---|---|---|
Source title | srctitle | 3 | 30 | Result count, descending |
Affiliation | af-id | 3 | 30 | Result count, descending |
City | affilcity | 3 | 30 | Result count, descending |
Country | affilcountry | 3 | 30 | Result count, descending |
Subject area, using label | auth-subclus | 3 | All | Result count, descending |
Field | Facet Name | Default number of values to return counts for | Maximum number of values to return counts for | Sorting |
---|---|---|---|---|
City | affilcity | 3 | 30 | Result count, descending |
Country | affilcountry | 3 | 30 | Result count, descending |