TREC Search Engine

Project Structure

trec-engine
|-- README.md
|-- build.gradle
|-- dat // various data (see dependencies), not version-controlled
|-- eval // evaluation results, not version-controlled
|-- gradle
|-- gradlew
|-- gradlew.bat
|-- scripts // misc scripts
|-- settings.gradle
`-- src // java source files

Usage

usage: java -jar trec.jar
 -d,--docmap <arg>         build document map. default: ./dat/file.txt
 -e,--expansion <arg>      query expansion method for VSM mode: 0 for
                           none, 1 for weighted, 2 for pseudo relevance
                           feedback, 3 for local association analysis, 4
                           for local correlation analysis. default: 0
 -h,--help                 print this message
 -i,--index <arg>          build index for the given postings file.
                           default: ./dat/post.txt
 -k,--top-k <arg>          top k documents to retrieve. default: 1000
 -m,--mode <arg>           query mode: 0 for VSM, 1 for Proximity.
                           default: 0
 -o,--output <arg>         output file path. default: output.txt
 -p,--stopwords <arg>      stopwords file path. default:
                           ./dat/stopwords.txt
 -r,--retrieve <arg>       retrieve documents for the given query file.
                           default: ./dat/queryT.txt
 -t,--threads <arg>        number of threads to use. default: 10
 -x,--max-distance <arg>   maximum distance between two terms in a phrase
                           query. default: 10

Build

./gradlew build -x test

# Output in ./build/libs/trec.jar

The program can also be run without an explicit build step using the Gradle wrapper:

./gradlew run --args="..."

Data and Dependencies

Name	Version	Description
Java	8	Java SDK
Gradle	7.4	Build Tool
./dat/post.txt	NA	Postings File
./dat/file.txt	NA	Document Metadata
./dat/queryT.txt	NA	Query File (short)
./dat/queryTDN.txt	NA	Query File (long)
./dat/stopwords.txt	NA	Stopwords List
./eval/trec_eval	NA	Evaluation Tool
./eval/judgerobust	NA	Benchmarking File

Since the current indexing procesure is slow, a pre-built index is made available here. Refer to this post to understand how to use this file.

Examples

The following commands are run in the project root directory. You should also have a Redis server running and set up the proper environment variables.

export REDIS_HOST=localhost
export REDIS_PORT=6379

# Build inverted file index
./gradlew run --args="-i ./dat/post.txt -t 50"

# Build document map
./gradlew run --args="-d ./dat/file.txt"

# VSM Query
./gradlew run --args="-r ./dat/queryT.txt -o ./eval/T_VSM.ret -p ./dat/stopwords.txt -k 1000 -m 0 -e 0 -t 20"
./gradlew run --args="-r ./dat/queryTDN.txt -o ./eval/TDN_VSM.ret -p ./dat/stopwords.txt -k 1000 -m 0 -e 0 -t 20"

# Weighted VSM Query
./gradlew run --args="-r ./dat/queryTDN.txt -o ./eval/TDN_W.ret -p ./dat/stopwords.txt -k 1000 -m 0 -e 1 -t 20"

# Proximity Query
./gradlew run --args="-r ./dat/queryT.txt -o ./eval/T_P.ret -p ./dat/stopwords.txt -k 1000 -m 1 -e 1 -x 15 -t 20"

Evaluation

The TREC evaluation tool is available at https://github.com/usnistgov/trec_eval. You should install it to the ./eval folder.

# Generate evaluation results for all queries
for file in ./eval/*.ret; do
    ./eval/trec_eval ./eval/judgerobust $file > "${file%.ret}".eval
done

# Generate diagrams for the evaluation results
python3 ./scripts/plot.py -i `ls -1 ./eval/*.eval | tr '\n' ','` -o ./eval/PR.png,./eval/P.png