Ubuntu 9.10: Wifi connection fix

You have trouble connecting to the wireless network on UBuntu 9.10 try this

sudo apt-get install --reinstall bcmwl-kernel-source

 Hope that helps. It works for me now.

Cascading: How does cascading decides which fields should go to a column family?

I was playing with Cascading code sample as given here.

Problem Statement: let's say we have three fields in a tuple for e.g.

line_num, lower, upper, double
1, a, A, AA

and I wish to add double to its own column family or lets say club it with an existing column family 'right' How do I do that.

Solution:

String tableName = "DataLoadTable";
        Fields keyFields = new Fields("line_num");

// add a new family name
        String[] familyNames = new String[] { "left", "right", "double" };

// group your fields together in the order in which you would like them to be 

// added to column families
        Fields[] valueFields = new Fields[] { new Fields("lower"),
                new Fields("upper"), new Fields("double") };
        HBaseScheme hbaseScheme = new HBaseScheme(keyFields, familyNames,
                valueFields);
        Tap sink = new HBaseTap(tableName, hbaseScheme, SinkMode.REPLACE);

// describe your tuple entry: add the new field
        Fields fieldDeclaration = new Fields("line_num", "lower", "upper",
                "double");
        Function function = new RegexSplitter(fieldDeclaration, ", ");

The remaining of the code remains the same as given in the example.

Either, the above was too obvious that the authors didn't talked about it in the user guide or I do not know how to describe the problem and hence was not able to find them.

Let me know if I'm wrong.

Running Java in debug mode using Apache Ant

Configure your Java task as given below;

<java classname="org.zero.Main" fork="true" failonerror="true">
            <sysproperty key="DEBUG" value="true" />
            <jvmarg value="-Xdebug" />
            <jvmarg value="-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8999" />
            <jvmarg value="-Xnoagent" />
            <jvmarg value="-Djava.compiler=none" />
            <arg value="${project.root}/conf/preferences.xml" />
            <classpath refid="project.classpath" />
        </java>

Further,  configure your eclipse debug remote application to listen to the specified port (8999 in this case).

Also, add Thread.sleep(1000); as the first line in your main method.

Execute Java task and try connecting from eclipse, you may need to increase the thread sleep time.

Tip: Sort a map by values

A handy tip to sort map by values.

//:~
package samples.core.java;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

public class SortMapByValueExample {
public static void main(String[] args) {
Map map = new TreeMap();
map.put("1", "100");
map.put("10", "50");
map.put("100", "40");
map.put("1000", "10000");

List keys = new ArrayList(map.keySet());
ByValueComparator bvc = new SortMapByValueExample().new ByValueComparator(
map);
Collections.sort(keys, bvc);
Iterator iterator = keys.iterator();
while (iterator.hasNext()) {
String key = (String) iterator.next();
System.out.println(key + "-" + map.get(key));
}
}

private class ByValueComparator implements Comparator {
private Map map;

public ByValueComparator(Map map) {
this.map = map;
}

public int compare(Object o1, Object o2) {
int integer = Integer.parseInt((String) this.map.get((String) o1));
int otherInteger = Integer.parseInt((String) this.map
.get((String) o2));
return -1
* (new Integer(integer)
.compareTo(new Integer(otherInteger)));
}
}
}