Update collab-filter.py for Including Pearson Calculation

collab-filter.py

@@ -36,4 +36,41 @@ for i in range(10):
 data.append(userRatings)
 file.close()
 userFile.close()
-#data is complete at this point
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+#data is complete at this point
+
+# Pearson Correlation Basic Implementation Using for Loop
+pearson = []
+rows = len(data)
+users = data[rows-1]
+cols = len(users)
+for x in range(1,rows-1): # does not include (rows-1)
+	lis = data[x]
+	sumprod = 0
+	sumx = 0
+	sumy = 0
+	sumx2 = 0
+	sumy2 = 0
+	n = 0
+	for y in range(1,cols):
+		if(float(lis[y]) != -1 and float(users[y]) != -1):
+			sumprod += float(lis[y])*float(users[y])
+			sumx += float(lis[y])
+			sumy += float(users[y])
+			sumx2 += float(lis[y]) ** 2
+			sumy2 += float(users[y]) ** 2
+			n += 1
+	
+	if(n > 0):
+		nume = n*sumprod - sumx*sumy
+		deno = (n*sumx2 - sumx**2) * (n*sumy2 - sumy**2)
+		deno = deno ** 0.5
+		if(deno > 0):
+			summ = nume / deno
+		else:
+			summ = 1
+		pearson.append((summ,lis[0]))
+	else:
+		pearson.append((0,lis[0]))
+
+pearson.sort(reverse=True)
+print(pearson)
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