Here is an implementation of collaborative filtering system, which is the most popular algorithm for recommender systems.

More information can be obtained from the slider: report/OpenCF-report.pdf

OpenCF implemented both user-based CF and item-based CF, and optimizing methods like:

1. Row normalization for Rating matrix.
2. Similarity functions:
   • raw cosine
   • adjusted cosine
   • pearson correlation
3. Similarity Summing:
   • Direct summing
   • Normalized(1-order) similarity summing
   • Probability similarity summing

compact is used to compact discontinuous user-id and item-id.

# compact data/uir to data/uir.compact, -U and -I specifies mapping file names, which is used to restore ids.
./compact -f data/uir -o data/uir.compact -U data/user.map -I data/item.map

# help
./compact -h

similarity computes similarity matrix, with various methods.

# help
./similarity -h

# raw cosine similarity
./similarity -f data/uir.compact -o data/ii.cos

# adjusted cosine similarity
./similarity -a 1 data/uir.compact -o data/ii.acos

# pearson correlation similarity
./similarity -a 2 data/uir.compact -o data/ii.corr

The data format similarity accept is:

userid1 itemid1 rating1
userid2 itemid2 rating2
...

where userid and itemid are int compatible, ratings are float compatible.

prediction uses similarity-file and rating-file to compute prediction matrix.

./predict -s data/ii.cos -f data/uir.compact -o data/uip.ii.compact

Use compact -r to restore user/item ids, mapping-files should be specified.

./compact -r -f data/uip.ii.compact -o data/uip.ii -U data/user.map -I data/item.map 

Dataset data/train and data/test are extracted from data/t_alibaba_data.csv manually. The format in train is not compatible. rating is used to generate compatible rating-file from data-files with this format:

userid1 itemid1 operation1  month1  day1
userid2 itemid2 operation2  month2  day2
...

# generate compatible rating-file: data/uir
rating/rating -i data/train -o data/uir -l data/dealdate.last -c data/deal.count

# help
rating/rating

postprocess is used to de-emphasize items that already purchased by user.

postprocess/postprocess -p data/uip.ii -l data/dealdate.last -c data/deal.count -o data/uip.ii.mod

# prepare test-file, generates data/test.ui
evaluate/prepare_test.sh data/test

# sort and filter prediction-file data/uip.ii to data/ii.ui
evaluate/sort_prediction.sh data/uip.ii

# evaluate sorted-prediction-file data/uip.ii.ui
evaluate/evaluate -p data/uip.ii.ui -t data/test.ui -o data/ii.curve