R: Highlighting search

solr_highlight {solrium} | R Documentation

## Highlighting search

### Description

Returns only highlight items

### Usage

    solr_highlight(conn, name = NULL, params = NULL, body = NULL,
      callopts = list(), raw = FALSE, parsetype = "df", ...)

### Arguments

`conn` | A solrium connection object, see SolrClient
`name` | Name of a collection or core. Or leave as `NULL` if not needed.
`params` | (list) a named list of parameters, results in a GET reqeust as long as no body parameters given
`body` | (list) a named list of parameters, if given a POST request will be performed
`callopts` | Call options passed on to [crul::HttpClient]
`raw` | (logical) If TRUE (default) raw json or xml returned. If FALSE, parsed data returned.
`parsetype` | One of list of df (data.frame)
`...` | Further args to be combined into query

### Value

XML, JSON, a list, or data.frame

### Facet parameters

- q Query terms. See examples.

- hl.fl A comma-separated list of fields for which to generate highlighted snippets. If left blank, the fields highlighted for the LuceneQParser are the defaultSearchField (or the df param if used) and for the DisMax parser the qf fields are used. A '*' can be used to match field globs, e.g. 'text_*' or even '*' to highlight on all fields where highlighting is possible. When using '*', consider adding hl.requireFieldMatch=TRUE.

- hl.snippets Max no. of highlighted snippets to generate per field. Note: it is possible for any number of snippets from zero to this value to be generated. This parameter accepts per-field overrides. Default: 1.

- hl.fragsize The size, in characters, of the snippets (aka fragments) created by the highlighter. In the original Highlighter, "0" indicates that the whole field value should be used with no fragmenting. See http://wiki.apache.org/solr/HighlightingParameters for more info.

- hl.q Set a query request to be highlighted. It overrides q parameter for highlighting. Solr query syntax is acceptable for this parameter.

- hl.mergeContiguous Collapse contiguous fragments into a single fragment. "true" indicates contiguous fragments will be collapsed into single fragment. This parameter accepts per-field overrides. This parameter makes sense for the original Highlighter only. Default: FALSE.

- hl.requireFieldMatch If TRUE, then a field will only be highlighted if the query matched in this particular field (normally, terms are highlighted in all requested fields regardless of which field matched the query). This only takes effect if "hl.usePhraseHighlighter" is TRUE. Default: FALSE.

- hl.maxAnalyzedChars How many characters into a document to look for suitable snippets. This parameter makes sense for the original Highlighter only. Default: 51200. You can assign a large value to this parameter and use hl.fragsize=0 to return highlighting in large fields that have size greater than 51200 characters.

- hl.alternateField If a snippet cannot be generated (due to no terms matching), you can specify a field to use as the fallback. This parameter accepts per-field overrides.

- hl.maxAlternateFieldLength If hl.alternateField is specified, this parameter specifies the maximum number of characters of the field to return. Any value less than or equal to 0 means unlimited. Default: unlimited.

- hl.preserveMulti Preserve order of values in a multiValued list. Default: FALSE.

- hl.maxMultiValuedToExamine When highlighting a multiValued field, stop examining the individual entries after looking at this many of them. Will potentially return 0 snippets if this limit is reached before any snippets are found. If maxMultiValuedToMatch is also specified, whichever limit is hit first will terminate looking for more. Default: Integer.MAX_VALUE

- hl.maxMultiValuedToMatch When highlighting a multiValued field, stop examining the individual entries after looking at this many matches are found. If maxMultiValuedToExamine is also specified, whichever limit is hit first will terminate looking for more. Default: Integer.MAX_VALUE

- hl.formatter Specify a formatter for the highlight output. Currently the only legal value is "simple", which surrounds a highlighted term with a customizable pre- and post text snippet. This parameter accepts per-field overrides. This parameter makes sense for the original Highlighter only.

- hl.simple.pre The text which appears before and after a highlighted term when using the simple formatter. This parameter accepts per-field overrides. The default values are "<em>" and "</em>" This parameter makes sense for the original Highlighter only. Use hl.tag.pre and hl.tag.post for FastVectorHighlighter (see example under hl.fragmentsBuilder)

- hl.simple.post The text which appears before and after a highlighted term when using the simple formatter. This parameter accepts per-field overrides. The default values are "<em>" and "</em>" This parameter makes sense for the original Highlighter only. Use hl.tag.pre and hl.tag.post for FastVectorHighlighter (see example under hl.fragmentsBuilder)

- hl.fragmenter Specify a text snippet generator for highlighted text. The standard fragmenter is gap (which is so called because it creates fixed-sized fragments with gaps for multi-valued fields). Another option is regex, which tries to create fragments that "look like" a certain regular expression. This parameter accepts per-field overrides. Default: "gap"

- hl.fragListBuilder Specify the name of SolrFragListBuilder. This parameter makes sense for FastVectorHighlighter only. To create a fragSize=0 with the FastVectorHighlighter, use the SingleFragListBuilder. This field supports per-field overrides.

- hl.fragmentsBuilder Specify the name of SolrFragmentsBuilder. This parameter makes sense for FastVectorHighlighter only.

- hl.boundaryScanner Configures how the boundaries of fragments are determined. By default, boundaries will split at the character level, creating a fragment such as "uick brown fox jumps over the la". Valid entries are breakIterator or simple, with breakIterator being the most commonly used. This parameter makes sense for FastVectorHighlighter only.

- hl.bs.maxScan Specify the length of characters to be scanned by SimpleBoundaryScanner. Default: 10. This parameter makes sense for FastVectorHighlighter only.

- hl.bs.chars Specify the boundary characters, used by SimpleBoundaryScanner. This parameter makes sense for FastVectorHighlighter only.

- hl.bs.type Specify one of CHARACTER, WORD, SENTENCE and LINE, used by BreakIteratorBoundaryScanner. Default: WORD. This parameter makes sense for FastVectorHighlighter only.

- hl.bs.language Specify the language for Locale that is used by BreakIteratorBoundaryScanner. This parameter makes sense for FastVectorHighlighter only. Valid entries take the form of ISO 639-1 strings.

- hl.bs.country Specify the country for Locale that is used by BreakIteratorBoundaryScanner. This parameter makes sense for FastVectorHighlighter only. Valid entries take the form of ISO 3166-1 alpha-2 strings.

- hl.useFastVectorHighlighter Use FastVectorHighlighter. FastVectorHighlighter requires the field is termVectors=on, termPositions=on and termOffsets=on. This parameter accepts per-field overrides. Default: FALSE

- hl.usePhraseHighlighter Use SpanScorer to highlight phrase terms only when they appear within the query phrase in the document. Default: TRUE.

- hl.highlightMultiTerm If the SpanScorer is also being used, enables highlighting for range/wildcard/fuzzy/prefix queries. Default: FALSE. This parameter makes sense for the original Highlighter only.

- hl.regex.slop Factor by which the regex fragmenter can stray from the ideal fragment size (given by hl.fragsize) to accomodate the regular expression. For instance, a slop of 0.2 with fragsize of 100 should yield fragments between 80 and 120 characters in length. It is usually good to provide a slightly smaller fragsize when using the regex fragmenter. Default: .6. This parameter makes sense for the original Highlighter only.

- hl.regex.pattern The regular expression for fragmenting. This could be used to extract sentences (see example solrconfig.xml) This parameter makes sense for the original Highlighter only.

- hl.regex.maxAnalyzedChars Only analyze this many characters from a field when using the regex fragmenter (after which, the fragmenter produces fixed-sized fragments). Applying a complicated regex to a huge field is expensive. Default: 10000. This parameter makes sense for the original Highlighter only.

- start Record to start at, default to beginning.

- rows Number of records to return.

- wt (character) Data type returned, defaults to 'json'. One of json or xml. If json, uses `fromJSON` to parse. If xml, uses `xmlParse` to parse. csv is only supported in `solr_search` and `solr_all`.

- fl Fields to return

- fq Filter query, this does not affect the search, only what gets returned

### References

See http://wiki.apache.org/solr/HighlightingParameters for more information on highlighting.

### See Also

`solr_search()`, `solr_facet()`

### Examples

    ## Not run:
    # connect
    (conn <- SolrClient$new(host = "api.plos.org", path = "search", port = NULL))

    # highlight search
    solr_highlight(conn, params = list(q='alcohol', hl.fl = 'abstract', rows=10),
      parsetype = "list")
    solr_highlight(conn, params = list(q='alcohol', hl.fl = c('abstract','title'),
      rows=3), parsetype = "list")

    # Raw data back
    ## json
    solr_highlight(conn, params = list(q='alcohol', hl.fl = 'abstract', rows=10),
       raw=TRUE)
    ## xml
    solr_highlight(conn, params = list(q='alcohol', hl.fl = 'abstract', rows=10,
       wt='xml'), raw=TRUE)
    ## parse after getting data back
    out <- solr_highlight(conn, params = list(q='theoretical math',
       hl.fl = c('abstract','title'), hl.fragsize=30, rows=10, wt='xml'),
       raw=TRUE)
    solr_parse(out, parsetype='list')

    ## End(Not run)

[Package solrium version 1.0.0 Index]