Adding source code for chapter 8

Chapter8/casestudy/casestudy1.py

@@ -0,0 +1,22 @@
+#casestudy1: Pi calculater
+from operator import add
+from random import random
+
+from pyspark.sql import SparkSession
+
+spark = SparkSession.builder.master("spark://192.168.64.2:7077") \
+    .appName("Pi claculator app") \
+    .getOrCreate()
+
+partitions = 2
+n = 10000000 * partitions
+
+
+def f(_):
+    x = random() * 2 - 1
+    y = random() * 2 - 1
+    return 1 if x ** 2 + y ** 2 <= 1 else 0
+
+
+count = spark.sparkContext.parallelize(range(1, n + 1), partitions).map(f).reduce(add)
+print("Pi is roughly %f" % (4.0 * count / n))