searcher.py

import numpy as np
import csv

class Searcher:
    def __init__(self, indexPath):
        # Store index.csv path
        self.indexPath = indexPath

    def search(self, queryFeature, limit = 10):
        # initialize directory of results
        results = {}

        # open the index file for reading
        with open(self.indexPath) as f:
            #initiate the CSV reader
            reader = csv.reader(f)

            for row in reader:
                features = [float(x) for x in row[1:]]
                d = self.chi2_distance(features, queryFeature)

                results[row[0]] = d 

            f.close()

        results = sorted([(v, k) for (k, v) in results.items()])

        return results[:limit]

    def chi2_distance(self, histA, histB, eps = 1e-10):
        d = 0.5 * np.sum([((a - b) ** 2) / (a + b + eps) 
            for (a,b) in zip(histA, histB)])

        return d