R to Solr Interface.

Description

The `rsolr` package is an idiomatic R interface to Solr based on deferred evaluation. A Solr core is represented as a data frame or list that supports Solr-side filtering, sorting, transformation and aggregation, all through the familiar base R API. Queries are processed lazily, i.e., a query is only sent to the database when the data are required.

Features

• Store, retrieve and compute on data with Solr, from R
• Use familiar R syntax and function names from the base R API, with some extensions
• Model data as either a data.frame or list, or use the low-level query API
• Conveniently manipulate document collections after retrieval
• Autogenerate a Solr schema from a data.frame
• Experiment with the embedded Solr instance
• Extend to support additional/custom Solr features

Example using data from R

This is inspired by some manipulations in the dplyr vignette.

Load the New York City 2013 flight data and upload to Solr:

library(nycflights13)
schema <- deriveSolrSchema(flights)
solr <- rsolr:::TestSolr(schema)
sr <- SolrFrame(solr$uri)
sr[] <- flights

Filtering:

subset(sr, month == 1 & day == 1)
head(sr, 10L)

Sorting:

sort(sr, by = ~ year + month + day)

Select fields:

subset(sr, select=c(year, month, day))
sr[c("year", "month", "day")]
sr[c("arr_*", "dep_*")] # Solr globs

Transform:

sr2 <- transform(sr,
                 gain = arr_delay - dep_delay,
                 speed = distance / air_time * 60)
sr2[c("gain", "speed")]

Aggregate:

unique(sr["tailnum"])
aggregate(~ tailnum, sr,
          count = TRUE,
          dist = mean(distance, na.rm=TRUE),
          delay = mean(arr_delay, na.rm=TRUE))

Example using existing Solr core

Construct a SolrFrame using the URL to the existing core:

sr <- SolrFrame("http://my.host.com/solr/mycore")
	

Convert the SolrFrame to a data.frame, typically after some filtering or aggregation:

df <- as.data.frame(sr)