solr_highlight: Do highlighting searches, outputing highlight only.

Description

Do highlighting searches, outputing highlight only.

Usage

solr_highlight(q, hl.fl = NULL, hl.snippets = NULL, hl.fragsize = NULL, hl.q = NULL, hl.mergeContiguous = NULL, hl.requireFieldMatch = NULL, hl.maxAnalyzedChars = NULL, hl.alternateField = NULL, hl.maxAlternateFieldLength = NULL, hl.preserveMulti = NULL, hl.maxMultiValuedToExamine = NULL, hl.maxMultiValuedToMatch = NULL, hl.formatter = NULL, hl.simple.pre = NULL, hl.simple.post = NULL, hl.fragmenter = NULL, hl.fragListBuilder = NULL, hl.fragmentsBuilder = NULL, hl.boundaryScanner = NULL, hl.bs.maxScan = NULL, hl.bs.chars = NULL, hl.bs.type = NULL, hl.bs.language = NULL, hl.bs.country = NULL, hl.useFastVectorHighlighter = NULL, hl.usePhraseHighlighter = NULL, hl.highlightMultiTerm = NULL, hl.regex.slop = NULL, hl.regex.pattern = NULL, hl.regex.maxAnalyzedChars = NULL, start = 0, rows = NULL, wt = "json", raw = FALSE, key = NULL, base = NULL, callopts = list(), fl = "DOES_NOT_EXIST", fq = NULL, parsetype = "list", verbose = TRUE)

Arguments

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 "" and "" 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

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.

(character) Data format to return. One of xml or json (default).

raw

(logical) If TRUE (default) raw json or xml returned. If FALSE, parsed data returned.

key

API key, if needed.

base

URL endpoint

callopts

Call options passed on to httr::GET

Fields to return

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

parsetype

One of list of df (data.frame)

verbose

If TRUE (default) the url call used printed to console.

Value

XML, JSON, a list, or data.frame

References

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

Examples

Run this code

## Not run: 
# url <- 'http://api.plos.org/search'
# 
# solr_highlight(q='alcohol', hl.fl = 'abstract', rows=10, base = url)
# solr_highlight(q='alcohol', hl.fl = c('abstract','title'), rows=3, base = url)
# 
# # Raw data back
# ## json
# solr_highlight(q='alcohol', hl.fl = 'abstract', rows=10, base = url,
#    raw=TRUE)
# ## xml
# solr_highlight(q='alcohol', hl.fl = 'abstract', rows=10, base = url,
#    raw=TRUE, wt='xml')
# ## parse after getting data back
# out <- solr_highlight(q='alcohol', hl.fl = c('abstract','title'), hl.fragsize=30,
#    rows=10, base = url, raw=TRUE, wt='xml')
# solr_parse(out, parsetype='df')
# ## End(Not run)