'Added Java functional programming tutorial and excercises;'

07_OpenMP/desc

@@ -8,6 +8,12 @@ Hints:
 * add -fopenmp to gcc compiler
 * add -lgomp (in Linux) to linker
 
+Or in the console one can run the command:
+
+$ gcc -fopenmp openmp1.c -lgomp
+
+And the file 'a.out' should be created. Execute this file.
+
 
 Excercise 2
 Implement in OpenMP the search of the maximum value in an array with randomly generated numbers. Check the speed up from 1 up to X threads. 

07_OpenMP/ex1/src/openmp1.c

@@ -1,59 +1,57 @@
-/*
- ============================================================================
- Name        : openmp1.c
- Author      : 
- Version     :
- Copyright   : Your copyright notice
- Description : Hello World in C, Ansi-style
- ============================================================================
- */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <omp.h>
+#include <time.h>
 
+void maks(int numThreads, int my_array[])
+{
+    int globMaks = 0;
+    int threadMaks = 0;
+    int a = 10;
+    clock_t start = clock();
+    omp_set_num_threads(numThreads);
+    #pragma omp parallel private(threadMaks) shared(globMaks)
+    {
+        #pragma omp for
+        for (int i = 0; i < a; i++)
+        {
+            if (my_array[i] > threadMaks)
+            {
+                threadMaks = my_array[i];
+            }
+        }
 
-void sum() {
-	int partial_Sum, total_Sum;
-
-	#pragma omp parallel private(partial_Sum) shared(total_Sum)
-	{
-		partial_Sum = 0;
-		total_Sum = 0;
-
-		#pragma omp for
-		for(int i = 1; i <= 10; i++) {
-			partial_Sum += i;
-		}
-
-		//Create thread safe region.
-		#pragma omp critical
-		{
-			//add each threads partial sum to the total sum
-			total_Sum += partial_Sum;
-		}
-	}
-	printf("Total Sum: %d\n", total_Sum);
+        #pragma omp critical
+        {
+            if (threadMaks > globMaks)
+            {
+                globMaks = threadMaks;
+            }
+        }
+    }
+    clock_t end = clock();
+    float seconds = (float)(end - start) / CLOCKS_PER_SEC;
+    printf("\n%d maksymalna dla %d watkow, czas: %f \n", globMaks, numThreads, seconds);
+    printf("\n");
 }
 
+
 int main(void) {
-	puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */
+    const int a = 10;
+    int my_array[a];
+    srand(time(NULL));
+    for (int i = 0; i < a; i++) {
+        my_array[i] = rand();
+    }
 
-	const int numThreads = 4;
-	int a[numThreads];
-	omp_set_num_threads(numThreads);
-	#pragma omp parallel
-	{
-		int id = omp_get_thread_num();
-		a[id] = id + 1;
-	}
+    for (int i = 0; i < a; i++) {
+        printf("%d ", my_array[i]);
+    }
 
-	for (int i = 0; i < numThreads; i++) {
-		printf("Hello from thread %d\n", a[i]);
-	}
+    int globMaks;
+    int threadMaks = 0;
 
-	sum();
-//	sum2();
+    maks(2, my_array);
 
-	return EXIT_SUCCESS;
+    return EXIT_SUCCESS;
 }

09_JavaFP/ex.txt

@@ -0,0 +1,10 @@
+1. Write Lambda expression in Java which implements sum of two integers
+
+2. Write Lambda expression in Java which removes duplicates from a list
+
+3. Write Lambda expression in Java which capitalize all strings
+
+4. Write Lambda expression in Java which finds all even and odd numbers
+
+5. Write Lambda expression in Java which finds the average length of strings in a list.
+

09_JavaFP/src/net/hypki/wmi/javafp/ArraysFunctionalProgramming.java

@@ -0,0 +1,55 @@
+package net.hypki.wmi.javafp;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Consumer;
+
+public class ArraysFunctionalProgramming {
+
+	// Java program to demonstrate an
+	// external iterator
+	public static void printArrayWithIterator() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+
+		// External iterator, for Each loop
+		for (Integer n : numbers) {
+			System.out.print(n + " ");
+		}
+		System.out.println();
+	}
+
+	public static void printArrayWithIndices() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+
+		// External iterator, with indices
+		for (int i = 0; i < numbers.size(); i++) {
+			System.out.print(numbers.get(i) + " ");
+		}
+		System.out.println();
+	}
+
+	public static void printArrayWithLambdas() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+
+		// Internal iterator
+		numbers.forEach(number -> System.out.print(number + " "));
+		System.out.println();
+		
+		// it is the same as implementing interfaces, but with interfaces it is a little bit more ugly
+		numbers.forEach(new Consumer<Integer>() {
+			@Override
+			public void accept(Integer t) {
+				System.out.print(t + " ");
+			}
+		});
+		System.out.println();
+	}
+
+	public static void main(String[] args) {
+		printArrayWithIterator();
+
+		printArrayWithIndices();
+		
+		printArrayWithLambdas();
+	}
+}

09_JavaFP/src/net/hypki/wmi/javafp/FunctionChaining.java

@@ -0,0 +1,39 @@
+package net.hypki.wmi.javafp;
+
+import java.util.function.Function;
+import java.util.logging.Logger;
+
+public class FunctionChaining {
+
+    static Logger logger = Logger.getLogger(FunctionChaining.class.getName());
+
+    private static Function<Integer, Integer> multiply = x -> x * 2;
+
+    private static Function<Integer, Integer> add = x -> x + 2;
+
+    private static Function<Integer, Integer> logOutput = x -> {
+        logger.info("Data:" + x);
+        return 0;
+    };
+
+    public static void execute(Integer input) {
+        Function<Integer, Integer> pipeline = multiply
+                                               .andThen(add)
+                                               .andThen(logOutput);
+        pipeline.apply(input);
+    }
+    
+    public static void execute2(Integer input) {
+        multiply
+           .andThen(add)
+           .andThen(logOutput)
+        	.apply(input);
+    }
+
+    public static void main(String[] args) {
+        execute(10);
+        
+        execute2(10);
+    }
+
+}

09_JavaFP/src/net/hypki/wmi/javafp/ImperativeVsDeclarative.java

@@ -0,0 +1,70 @@
+package net.hypki.wmi.javafp;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class ImperativeVsDeclarative {
+	public static void imperative() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+
+		int result = 0;
+		for (Integer n : numbers) {
+			if (n % 2 == 0) {
+				result += n * 2;
+			}
+		}
+		System.out.println(result);
+	}
+
+	public static void declarative() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+
+		System.out.println(numbers
+							.stream()
+							.filter(number -> number % 2 == 0) // 1.
+							.mapToInt(e -> e * 2) // Closure
+							.sum());
+		
+		// 1. Lambda expressions: A Lambda expression is an anonymous method that has mutability at very minimum and it has only a parameter list and a body. 
+		
+		// 2. in the above code of declarative style, every function is a pure function and pure functions don’t have side effects.
+		
+		// 3. lambdas are stateless and closure has immutable state. It means in any circumstances, the closure could not be mutable.
+	}
+	
+	public static void immutable() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+		
+		int factor = 2;
+		System.out.println(numbers
+							.stream()
+							.filter(number -> number % 2 == 0)
+							.mapToInt(e -> e * factor)
+							.sum());
+	}
+	
+	public static void NOTimmutable() {
+		List<Integer> numbers = Arrays.asList(11, 22, 33, 44, 55, 66, 77, 88, 99, 100);
+		
+		int factor = 2;
+		System.out.println(numbers
+							.stream()
+							.filter(number -> number % 2 == 0)
+							.mapToInt(e -> e * factor)
+							.sum());
+//		factor = 3;// uncomment this
+		
+		// * the variable factor is by default being considered as final. 
+		// * we should never try mutating any variable which is used inside pure functions == that would violate pure functions rules 
+		// which says pure function should neither change anything nor depend on anything that changes
+	}
+
+	public static void main(String[] args) {
+		imperative();
+		
+		declarative();
+		
+		immutable();
+		NOTimmutable();
+	}
+}

09_JavaFP/src/net/hypki/wmi/javafp/Parallel.java

@@ -0,0 +1,94 @@
+package net.hypki.wmi.javafp;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class Parallel {
+
+	public static void main(String[] args) {
+		// forEach
+		System.out.println("Printing list: ");
+		Arrays
+			.asList(1,2,3)
+			.forEach(System.out::println); // Consumer
+		// print output -> 1 2 3
+		
+		
+		// map
+		System.out.println("Computing squares (with limit and sort): ");
+		List<Integer> numbers = Arrays.asList(2,3,4,5);
+		numbers.stream()
+		  .map(x -> x *x) // Function
+		  .sorted()
+		  .limit(2)
+		  .collect(Collectors.toList())
+		  .forEach(System.out::println);;
+		// print output -> [4, 9]
+		
+		// filter
+		System.out.println("Filtering list of strings: ");
+		List<String> names = Arrays.asList("Sally", "Harry", "Sephora");
+		names
+			.stream()
+			.filter(s -> s.startsWith("S")) // Predicate
+			.collect(Collectors.toList())
+			.forEach(System.out::println);;
+		// print output -> [Sally, Sephora]
+			
+		// sorted
+			System.out.println("Sorting names: ");
+		names.stream()
+		  .sorted()
+		  .collect(Collectors.toList())
+		  .forEach(System.out::println);;
+		// print output -> [Harry, Sally, Sephora]
+		  
+		// reduce
+		System.out.println("Printing even numbers: ");
+		numbers.stream()
+				  .filter(x -> x % 2 == 0)
+				  .collect(Collectors.toList())
+				  .forEach(System.out::println);
+		
+		int even = numbers.stream()
+		  .filter(x -> x % 2 == 0) // Predicate
+		  .reduce(4, Integer::sum); // BinaryOperator which extends BiFunction
+		// print output -> 10
+		System.out.println("Sum of even numbers (+4 initial value): " + even);  
+		  
+		// max
+		int maxN = numbers
+				.stream()
+				.max(Integer::compare)
+				.get(); // Comparator
+		// print output -> 5
+		System.out.println("Max value: " + maxN);
+		
+		// min
+		int minN = numbers
+				.stream()
+				.min(Integer::compare)
+				.get(); // Comparator
+		// print output -> 2
+		System.out.println("Min value: " + minN);
+		
+		// skip
+		System.out.println("Skipping first number: ");
+		numbers
+			.stream()
+			.skip(1)
+			.collect(Collectors.toList())
+			.forEach(System.out::println);;
+		// print output -> [3,4,5]
+		
+		System.out.println("Computing squares in parallel: ");
+		numbers.stream()
+		  .parallel() // add this line here
+		  .map(x -> x *x)
+		  .sorted()
+		  .limit(2)
+		  .collect(Collectors.toList())
+		  .forEach(System.out::println);;
+	}
+}

09_JavaFP/src/net/hypki/wmi/javafp/RunnableFunctionalProgramming.java

@@ -0,0 +1,33 @@
+package net.hypki.wmi.javafp;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class RunnableFunctionalProgramming {
+
+	public static void runnableWithoutFunProgramming() {
+		Runnable r = new Runnable() {
+			public void run() {
+				System.out.println("Running in Runnable thread");
+			}
+		};
+
+		r.run();
+		System.out.println("Running in main thread");
+
+	}
+
+	public static void runnableWithFunProgramming() {
+		// lambda expression
+		Runnable r = () -> System.out.println("Running in Runnable thread");
+
+		r.run();
+		System.out.println("Running in main thread");
+	}
+
+	public static void main(String[] args) {
+		runnableWithoutFunProgramming();
+
+		runnableWithFunProgramming();
+	}
+}