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As an exercise I am trying to calculate a recursive EMA with a burn period in Esper, EPL. It has moderately complex startup logic, and I thought this would be a good test for evaluating the sorts of things Esper could achieve.
Assuming a stream of values x1, x2, x3 at regular intervals, we want to calculate:
let p = 0.1
a = average(x1, x2, x3, x4, x5) // Assume 5, in reality use a parameter
y1 = p * x1 + (p - 1) * a // Recursive calculation initialized with look-ahead average
y2 = p * x2 + (p - 1) * y1
y3 = p * x3 + (p - 1) * y2
....
The final stream should only publish y5, y6, y7, ...
I was toying with a context that produces an event containing the average a, and that event triggers a second context that begins the recursive calculations. But by the time I try to get the first context to trigger once and once only, and the second context to handle the initial case using a and subsequent events recursively I end up with a messy tangle of logic.
Is there a straight-forward way to approach this problem?
(I'm ignoring using a custom aggregator, since this is a learning exercise)
This doesn't answer the question, but might be useful - implementation as a custom aggregation function, tested with esper 7.1.0
public class EmaFactory implements AggregationFunctionFactory {
int burn = 0;
#Override
public void setFunctionName(String s) {
// Don't know why/when this is called
}
#Override
public void validate(AggregationValidationContext ctx) {
#SuppressWarnings("rawtypes")
Class[] p = ctx.getParameterTypes();
if ((p.length != 3)) {
throw new IllegalArgumentException(String.format(
"Ema aggregation required three parameters, received %d",
p.length));
}
if (
!(
(p[0] == Double.class || p[0] == double.class) ||
(p[1] == Double.class || p[1] == double.class) ||
(p[2] == Integer.class || p[2] == int.class))) {
throw new IllegalArgumentException(
String.format(
"Arguments to Ema aggregation must of types (Double, Double, Integer), got (%s, %s, %s)\n",
p[0].getName(), p[1].getName(), p[2].getName()) +
"This should be made nicer, see AggregationMethodFactorySum.java in the Esper source code for " +
"examples of correctly dealing with multiple types"
);
}
if (!ctx.getIsConstantValue()[2]) {
throw new IllegalArgumentException(
"Third argument 'burn' to Ema aggregation must be constant"
);
}
;
burn = (int) ctx.getConstantValues()[2];
}
#Override
public AggregationMethod newAggregator() {
return new EmaAggregationFunction(burn);
}
#SuppressWarnings("rawtypes")
#Override
public Class getValueType() {
return Double.class;
}
}
public class EmaAggregationFunction implements AggregationMethod {
final private int burnLength;
private double[] burnValues;
private int count = 0;
private double value = 0.;
EmaAggregationFunction(int burn) {
this.burnLength = burn;
this.burnValues = new double[burn];
}
private void update(double x, double alpha) {
if (count < burnLength) {
value += x;
burnValues[count++] = x;
if (count == burnLength) {
value /= count;
for (double v : burnValues) {
value = alpha * v + (1 - alpha) * value;
}
// in case burn is long, free memory
burnValues = null;
}
} else {
value = alpha * x + (1 - alpha) * value;
}
}
#Override
public void enter(Object tmp) {
Object[] o = (Object[]) tmp;
assert o[0] != null;
assert o[1] != null;
assert o[2] != null;
assert (int) o[2] == burnLength;
update((double) o[0], (double) o[1]);
}
#Override
public void leave(Object o) {
}
#Override
public Object getValue() {
if (count < burnLength) {
return null;
} else {
return value;
}
}
#Override
public void clear() {
// I don't know when / why this is called - this part untested
count = 0;
value = 0.;
burnValues = new double[burnLength];
}
}
public class TestEmaAggregation {
private EPRuntime epRuntime;
private SupportUpdateListener listener = new SupportUpdateListener();
void send(int id, double value) {
epRuntime.sendEvent(
new HashMap<String, Object>() {{
put("id", id);
put("value", value);
}},
"CalculationEvent");
}
#BeforeEach
public void beforeEach() {
EPServiceProvider provider = EPServiceProviderManager.getDefaultProvider();
EPAdministrator epAdministrator = provider.getEPAdministrator();
epRuntime = provider.getEPRuntime();
ConfigurationOperations config = epAdministrator.getConfiguration();
config.addPlugInAggregationFunctionFactory("ema", EmaFactory.class.getName());
config.addEventType(
"CalculationEvent",
new HashMap<String, Object>() {{ put("id", Integer.class); put("value", Double.class); }}
);
EPStatement stmt = epAdministrator.createEPL("select ema(value, 0.1, 5) as ema from CalculationEvent where value is not null");
stmt.addListener(listener);
}
Double getEma() {
return (Double)listener.assertOneGetNewAndReset().get("ema");
}
#Test
public void someTest() {
send(1, 1);
assertEquals(null, getEma());
send(1, 2);
assertEquals(null, getEma());
send(1, 3);
assertEquals(null, getEma());
send(1, 4);
assertEquals(null, getEma());
// Last of the burn period
// We expect:
// a = (1+2+3+4+5) / 5 = 3
// y1 = 0.1 * 1 + 0.9 * 3 = 2.8
// y2 = 0.1 * 2 + 0.9 * 2.8
// ... leading to
// y5 = 3.08588
send(1, 5);
assertEquals(3.08588, getEma(), 1e-10);
// Outside burn period
send(1, 6);
assertEquals(3.377292, getEma(), 1e-10);
send(1, 7);
assertEquals(3.7395628, getEma(), 1e-10);
send(1, 8);
assertEquals(4.16560652, getEma(), 1e-10);
}
}
I want to identify the Expression like int a = function(b,c)， so I wrote the code as followers:
void foo(int* a, int *b) {
int x;
int m;
int z;
int *p;
if (a[0] > 1) {
b[0] = 2;
z=10;
x = function( sizeof(char));
}
m = function( sizeof(char));
bar(x,m);
}
void bar(float x, float y);
int function(int size){
return size;
}
And than I used clang -Xclang -ast-dump -fsyntax-only cfunc_with_if.c to get the AST of the code:
From the result I found the AST Node type of int a = function(b,c) is BinaryOperator. In order to verify this, I use VisitStmt(Stmt *s) to print out all stmts' type.
bool VisitStmt(Stmt *s) {
if(isa<Stmt>(s)) {
Stmt *Statement = dyn_cast<Stmt>(s);
//Statement->dump();
std::string st(Statement->getStmtClassName());
st = st + "\n";
TheRewriter.InsertText(Statement->getLocStart(), st, true, true);
}
return true;
}
But the result is so weird. There is nothing printed out about the type of int a = function(b,c). and I'm so confused about the result. Is there some error in my code or something else?
There's no output at bar(x,m); either. Are there any errors when the tool compiles the code being analyzed? As written above, the code would fail to compile at x = function( sizeof(char)); since function has not been declared. Even when compilation has failed due to errors, the libtool tools can still run at least partially, with strange results.
Edit to add: what happens if you run the tool on this code?
void bar(float x, float y);
int function(int size);
void foo(int* a, int *b) {
int x;
int m;
int z;
int *p;
if (a[0] > 1) {
b[0] = 2;
z=10;
x = function( sizeof(char));
}
m = function( sizeof(char));
bar(x,m);
}
void bar(float x, float y);
int function(int size){
return size;
}
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
import javax.imageio.ImageIO;
import java.awt.*;
class Multicore1 extends RecursiveAction
{
private int[] msource;
private int mstart;
private int mlength;
private int[] mDestination;
private int window=15;
private BufferedImage mimage;
public Multicore1(int[] src,int start,int length,int[] dest,BufferedImage image)
{
msource=src;
mstart=start;
mlength=length;
mDestination=dest;
mimage=image;
}
protected void computeDirectly(BufferedImage Img)
{
int rgb;
int lum;
int grayval;
int rgbVal;
int x,y;
int sliding=(window-1)/2;
System.out.println(" mlenght valu is " + mlength);
System.out.println(" mstart valu is " + mstart);
float r=0; float g=0;float b=0;
int red=0,green=0,blue=0;
// the image after conversion doesnot seem to be properly converted to grayscal. please look upon my code if there is any mistake
for(x=mstart;x <(double) mstart+mlength; x++)
{
for( y=sliding; y <= sliding; y++)
{
int mindex = Math.min(Math.max(x+y , 0), msource.length - 1);
rgb=msource[mindex];
//rgbVal = msource.getRGB(x,y);
r = (float)((rgb & 0xff0000) >>16 ) ;
g = (float)((rgb & 0x00ff00)>> 8);
b = (float)((rgb & 0x0000ff) >>0 ) ;
}
lum=(int) Math.round(0.2126*r+0.7152*g+0.0722*b);
grayval=(lum<<16)|(lum<<8)|lum;
mDestination[x] =(grayval);
}
}
protected static int sThreshold = 10000;
#Override
protected void compute() {
if (mlength < sThreshold) {
computeDirectly(mimage);
return;
}
int split = mlength / 2;
invokeAll(new Multicore1(msource, mstart, split, mDestination,mimage),
new Multicore1(msource, mstart + split, mlength - split,
mDestination,mimage));
}
public static void main(String args[]) throws Exception
{
BufferedImage image=ImageIO.read(new File("xyz.jpg"));
int w=image.getWidth();
int h=image.getHeight();
BufferedImage convertedimg=grayscale(w,h,image);
String dstName = "Gray.jpg";
File dstFile = new File(dstName);
ImageIO.write(convertedimg,"jpg",dstFile);
}
public static BufferedImage grayscale(int w,int h,BufferedImage image)
{
int[] src=image.getRGB(0, 0, w, h, null, 0, w);
int[] dst=new int[src.length];
System.out.println("hello");
System.out.println("Array size is " + src.length);
System.out.println("Threshold is " + sThreshold);
Multicore1 m1=new Multicore1(src,0,src.length,dst,image);
ForkJoinPool pool=new ForkJoinPool();
long starttime=System.currentTimeMillis();
pool.invoke(m1);
long endtime=System.currentTimeMillis();
System.out.println("Time took:" +(endtime-starttime));
BufferedImage dstimage=new BufferedImage(w,h,BufferedImage.TYPE_INT_ARGB);
//Color c=new Color(0,0,0);
dstimage.setRGB(0, 0, w, h, dst, 0, w);
//dstimage.setRGB(0,0,c.getRGB());
return dstimage;
}
}
grayval**=*(0xff000000)*|**(lum<<16)|(lum<<8)|lum;
You need to apply a mask before you move the bits.
I want to print all the possible solutions to LCS problem.
The two strings abcbdab and bdcaba should print following 3 strings:
bdab,bcba,bcab.
C is the global matrix table which takes values according to algorithm and m, n are the length of the sequences a, b.
But The output is something unexpected.
#include<stdio.h>
#include<conio.h>
int co=0,m=0,n=0,c[10][10];
char a[10],b[10];
void main()
{
int i,j;
clrscr();
printf("Enter Two strings: ");
scanf("%s",a);
scanf("%s",b);
m=strlen(a);
n=strlen(b);
for(i=0;i<=m;i++)
{
for(j=0;j<=n;j++)
{ if(i==0 || j==0)
{
c[i][j]=0;
}
else if(a[i-1]==b[j-1])
{
c[i][j]=c[i-1][j-1]+1;
}
else if(c[i-1][j]>=c[i][j-1])
{
c[i][j]=c[i-1][j];
}
else
{
c[i][j]=c[i][j-1];
}
}
}
for(i=0;i<=m;i++)
{
for(j=0;j<=n;j++)
{
printf("%d\t",c[i][j]);
}
printf("\n");
}
print(m,n);
getch();
}
print(int i,int j)
{
if(i==0 || j==0)
return 0;
else if(a[i-1]==b[j-1])
{
print(i-1,j-1);
if(co==c[m][n])
{
co=0;
printf("\n");
}
printf("%c",a[i-1]);
co++;
}
else if(c[i-1][j]==c[i][j-1])
{
print(i-1,j);
print(i,j-1);
}
else if(c[i][j-1]>=c[i-1][j])
print(i,j-1);
else
print(i-1,j);
return;
}
Here you can find a recursive approach of how to do this: Reading out all LCSs
Here is my code for this approach in Java:
private Set<String> lcs(int[][] dp, String fst, String snd, int i, int j) {
Set<String> lcss = new HashSet<>();
if (i == 0 || j == 0) {
lcss.add("");
} else if (fst.charAt(i - 1) == snd.charAt(j - 1)) {
for (String lcs : lcs(dp, fst, snd, i - 1, j - 1)) {
lcss.add(lcs + fst.charAt(i - 1));
}
} else {
if (dp[i - 1][j] >= dp[i][j - 1]) {
lcss.addAll(lcs(dp, fst, snd, i - 1, j));
}
if (dp[i][j - 1] >= dp[i - 1][j]) {
lcss.addAll(lcs(dp, fst, snd, i, j - 1));
}
}
return lcss;
}
Here is the Java code with comments explaining how to print all possible lcs.
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
public class LongestCommonSubsequence {
public static int[][] LCSmatrix(String X, String Y) {
//we ignore the top most row and left most column in this matrix
//so we add 1 and create a matrix with appropriate row and column size
int m = X.length() + 1, n = Y.length() + 1;
int[][] c = new int[m][n];
for (int i = 1; i < m; i++) {
for (int j = 1; j < n; j++) {
//since we added 1 to row size and column size,
// we substract 1 from i,j to find the char at that index
if (X.charAt(i - 1) == Y.charAt(j - 1)) {
c[i][j] = c[i - 1][j - 1] + 1;
} else if (c[i - 1][j] >= c[i][j - 1]) {
c[i][j] = c[i - 1][j];
} else {
c[i][j] = c[i][j - 1];
}
}
}
printMatrix(c);
return c;
}
public static void printMatrix(int[][] grid) {
for (int r = 0; r < grid.length; r++) {
for (int c = 0; c < grid[r].length; c++) {
System.out.print(grid[r][c] + " ");
}
System.out.println();
}
}
public static void allLCS(int[][] c, String X, String Y, int i, int j, Set<String> setLCS, String s) {
//return when either of the string length is 0
if (i == 0 || j == 0) {
setLCS.add(s);
return;
}
//if last characters are equal, they belong in lcs
if (X.charAt(i - 1) == Y.charAt(j - 1)) {
//prepend the char to lcs since, we are going backwards
s = X.charAt(i - 1) + s;
//continue finding lcs in substrings X.substring(0,i-1) and Y.substring(0,j-1)
allLCS(c, X, Y, i - 1, j - 1, setLCS, s);
} // if there is a tie in matrix cells, we backtrack in both ways,
// else one way, which ever is greater
else if (c[i - 1][j] == c[i][j - 1]) {
//continue finding lcs in substring X.substring(0,i-1)
allLCS(c, X, Y, i - 1, j, setLCS, s);
//continue finding lcs in substring Y.substring(0,j-1)
allLCS(c, X, Y, i, j - 1, setLCS, s);
} else if (c[i - 1][j] > c[i][j - 1]) {
allLCS(c, X, Y, i - 1, j, setLCS, s);
} else {
allLCS(c, X, Y, i, j - 1, setLCS, s);
}
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println(" Enter String X and Y : ");
String X = sc.next();
String Y = sc.next();
sc.close();
Set<String> set = new HashSet<String>();
allLCS(LCSmatrix(X, Y), X, Y, X.length(), Y.length(), set, "");
System.out.println(set.toString());
}
}
class Solution
{
public int function1(String s,String t,int n,int m,int dp[][]){
if(n==0 || m==0){
return 0;
}
if(dp[n][m]!=-1){
return dp[n][m];
}
if(s.charAt(n-1)==t.charAt(m-1)){
return dp[n][m]=1+function1(s,t,n-1,m-1,dp);
}
return dp[n][m]=Math.max(function1(s,t,n-1,m,dp),function1(s,t,n,m-1,dp));
}
public HashSet<String> function2(String s,String t,int n,int m,int dp[][],HashMap<String,HashSet<String>> map){
HashSet<String> temp=new HashSet<String>();
String key=n+"-"+m;
if(n==0 || m==0){
temp.add("");
return temp;
}
if(map.containsKey(key)){
return map.get(key);
}
if(s.charAt(n-1)==t.charAt(m-1)){
for(String tempstr:function2(s,t,n-1,m-1,dp,map)){
temp.add(tempstr+s.substring(n-1,n));
}
}
else{
if(dp[n-1][m]>=dp[n][m-1]){
temp.addAll(function2(s,t,n-1,m,dp,map));
}
if(dp[n-1][m]<=dp[n][m-1]){
temp.addAll(function2(s,t,n,m-1,dp,map));
}
}
map.put(key,temp);
return temp;
}
public List<String> all_longest_common_subsequences(String s, String t)
{
int n=s.length();
int m=t.length();
int dp[][]=new int[n+1][m+1];
for(int i=0;i<=n;i++){
for(int j=0;j<=m;j++){
dp[i][j]=-1;
}
}
function1(s,t,n,m,dp);
HashMap<String,HashSet<String>> map=new HashMap<String,HashSet<String>>();
ArrayList<String> ans=new ArrayList<String>(function2(s,t,n,m,dp,map));
Collections.sort(ans);
return ans;
}
}
Your source code is not printing the lcs. It is actually calculating the length of lcs. Source code given by you is totally wrong. First try to print one lcs. Then extend that solution to print all the lcs. For your help given below is working java solution.
static int arr[][];
static void lcs(String s1, String s2) {
for (int i = 1; i <= s1.length(); i++) {
for (int j = 1; j <= s2.length(); j++) {
if (s1.charAt(i - 1) == s2.charAt(j - 1))
arr[i][j] = arr[i - 1][j - 1] + 1;
else
arr[i][j] = Math.max(arr[i - 1][j], arr[i][j - 1]);
}
}
}
static Set<String> lcs(String s1, String s2, int len1, int len2) {
if (len1 == 0 || len2 == 0) {
Set<String> set = new HashSet<String>();
set.add("");
return set;
}
if (s1.charAt(len1 - 1) == s2.charAt(len2 - 1)) {
Set<String> set = lcs(s1, s2, len1 - 1, len2 - 1);
Set<String> set1 = new HashSet<>();
for (String temp : set) {
temp = temp + s1.charAt(len1 - 1);
set1.add(temp);
}
return set1;
} else {
Set<String> set = new HashSet<>();
Set<String> set1 = new HashSet<>();
if (arr[len1 - 1][len2] >= arr[len1][len2 - 1]) {
set = lcs(s1, s2, len1 - 1, len2);
}
if (arr[len1][len2 - 1] >= arr[len1 - 1][len2]) {
set1 = lcs(s1, s2, len1, len2 - 1);
}
for (String temp : set) {
set1.add(temp);
}
//System.out.println("In lcs" + set1);
return set1;
}
}
public static void main(String[] args) {
String s1 = "abcbdab";
String s2 = "bdcaba ";
arr = new int[s1.length() + 1][s2.length() + 1];
lcs(s1, s2);
System.out.println(lcs(s1, s2, s1.length(), s2.length()));
}
If last character of strings are equal then they must be in lcs. If they are not equal lcs will be either constructed from upper side of matrix or left side of matrix depending upon which value is greater. If both the value is equal then lcs will be constructed from both the side. So keep constructing the lcs until you have constructed all the lcs and store them in a set.
I'm stucked when implementing Barcode scanning in Blackberry 5.0 SDK, since I'm look into deep search on the internet, and found no clue.
Then I started to write my own class to provide Barcode Scanning (using zxing core)
then I need to implements BitmapLuminanceSource (rim version not Android version)
public class BitmapLuminanceSource extends LuminanceSource {
private final Bitmap bitmap;
public BitmapLuminanceSource(Bitmap bitmap){
super(bitmap.getWidth(),bitmap.getHeight());
this.bitmap = bitmap;
}
public byte[] getRow(int y, byte[] row) {
//how to implement this method
return null;
}
public byte[] getMatrix() {
//how to implement this method
return null;
}
}
Well, the javadoc in LuminanceSource tells you what it returns. And you have implementations like PlanarYUVLuminanceSource in android/ that show you an example of it in action. Did you look at these at all?
The quick answer though is that both return one row of the image, or the entire image, as an array of luminance values. There is one byte value per pixel and it should be treated as an unsigned value.
I've solved this problem.
Here's the BitmapLuminanceSource implementation
import net.rim.device.api.system.Bitmap;
import com.google.zxing.LuminanceSource;
public class BitmapLuminanceSource extends LuminanceSource {
private final Bitmap bitmap;
private byte[] matrix;
public BitmapLuminanceSource(Bitmap bitmap) {
super(bitmap.getWidth(), bitmap.getHeight());
int width = bitmap.getWidth();
int height = bitmap.getHeight();
this.bitmap = bitmap;
int area = width * height;
matrix = new byte[area];
int[] rgb = new int[area];
bitmap.getARGB(rgb, 0, width, 0, 0, width, height);
for (int y = 0; y < height; y++) {
int offset = y * width;
for (int x = 0; x < width; x++) {
int pixel = rgb[offset + x];
int luminance = (306 * ((pixel >> 16) & 0xFF) + 601
* ((pixel >> 8) & 0xFF) + 117 * (pixel & 0xFF)) >> 10;
matrix[offset + x] = (byte) luminance;
}
}
rgb = null;
}
public byte[] getRow(int y, byte[] row) {
if (y < 0 || y >= getHeight()) {
throw new IllegalArgumentException(
"Requested row is outside the image: " + y);
}
int width = getWidth();
if (row == null || row.length < width) {
row = new byte[width];
}
int offset = y * width;
System.arraycopy(this.matrix, offset, row, 0, width);
return row;
}
public byte[] getMatrix() {
return matrix;
}
}
I added com.google.zxing (library for Barcode encode/decode) to my project